Journal articles on the topic 'Developmental Delay Encephalopathy Functional Spectroscopy'

Background: The term developmental delay denotes a significant delay in one or more developmental domains in humans. The importance of evaluation of a child with developmental delay lies in early diagnosis and treatment and also parental counseling regarding the outcome of their child and to identify any possible risk of recurrence in the siblings. This study is done to evaluate Magnetic Resonance Imaging (MRI) as an investigative modality for evaluation and to correlate the spectrum of findings in such patients with developmental delay. Methods: This is a prospective observational study done at the Department of Radiodiagnosis, Jorhat Medical College and Hospital from January 2022 to December 2022 with a sample size of 12 cases. All patients were evaluated clinically and underwent an MRI of the brain performed using a 1.5 Tesla MRI scanner. MRI scan was done and findings are recorded. Results: Among the cases, 3 have white matter disorders, 3 cases have Hypoxic Ischemic Encephalopathy (HIE), 2 cases have Cerebral atrophy with encephalomalacic changes, 1 case showing sub-ependymal heterotopia and 3 cases have normal findings. Conclusions: The spectrum of developmental delay is wide and MRI brain helps in proper diagnosis. This leads to appropriate treatment and parent counselling. Further, advanced imaging modalities like Functional MRI, MR Spectroscopy, Diffusion Tensor Imaging etc. helps in further evaluation of developmental delay.

Abstract Loss-of-function mutations in glutaminase (GLS), the enzyme converting glutamine into glutamate, and the counteracting enzyme glutamine synthetase (GS) cause disturbed glutamate homeostasis and severe neonatal encephalopathy. We report a de novo Ser482Cys gain-of-function variant in GLS encoding GLS associated with profound developmental delay and infantile cataract. Functional analysis demonstrated that this variant causes hyperactivity and compensatory downregulation of GLS expression combined with upregulation of the counteracting enzyme GS, supporting pathogenicity. Ser482Cys-GLS likely improves the electrostatic environment of the GLS catalytic site, thereby intrinsically inducing hyperactivity. Alignment of +/−12.000 GLS protein sequences from >1000 genera revealed extreme conservation of Ser482 to the same degree as catalytic residues. Together with the hyperactivity, this indicates that Ser482 is evolutionarily preserved to achieve optimal—but submaximal—GLS activity. In line with GLS hyperactivity, increased glutamate and decreased glutamine concentrations were measured in urine and fibroblasts. In the brain (both grey and white matter), glutamate was also extremely high and glutamine was almost undetectable, demonstrated with magnetic resonance spectroscopic imaging at clinical field strength and subsequently supported at ultra-high field strength. Considering the neurotoxicity of glutamate when present in excess, the strikingly high glutamate concentrations measured in the brain provide an explanation for the developmental delay. Cataract, a known consequence of oxidative stress, was evoked in zebrafish expressing the hypermorphic Ser482Cys-GLS and could be alleviated by inhibition of GLS. The capacity to detoxify reactive oxygen species was reduced upon Ser482Cys-GLS expression, providing an explanation for cataract formation. In conclusion, we describe an inborn error of glutamate metabolism caused by a GLS hyperactivity variant, illustrating the importance of balanced GLS activity.

Mutations in the KCNA1 gene, encoding the voltage-gated potassium channel Kv1.1, have been associated with a spectrum of neurological phenotypes, including episodic ataxia type 1 and developmental and epileptic encephalopathy. We have recently identified a de novo variant in KCNA1 in the highly conserved Pro-Val-Pro motif within the pore of the Kv1.1 channel in a girl affected by early onset epilepsy, ataxia and developmental delay. Other mutations causing severe epilepsy are located in Kv1.1 pore domain. The patient was initially treated with a combination of antiepileptic drugs with limited benefit. Finally, seizures and ataxia control were achieved with lacosamide and acetazolamide. The aim of this study was to functionally characterize Kv1.1 mutant channel to provide a genotype–phenotype correlation and discuss therapeutic options for KCNA1-related epilepsy. To this aim, we transfected HEK 293 cells with Kv1.1 or P403A cDNAs and recorded potassium currents through whole-cell patch-clamp. P403A channels showed smaller potassium currents, voltage-dependent activation shifted by +30 mV towards positive potentials and slower kinetics of activation compared with Kv1.1 wild-type. Heteromeric Kv1.1+P403A channels, resembling the condition of the heterozygous patient, confirmed a loss-of-function biophysical phenotype. Overall, the functional characterization of P403A channels correlates with the clinical symptoms of the patient and supports the observation that mutations associated with severe epileptic phenotype cluster in a highly conserved stretch of residues in Kv1.1 pore domain. This study also strengthens the beneficial effect of acetazolamide and sodium channel blockers in KCNA1 channelopathies.

Branched-chain amino acids (BCAA) are essential amino acids playing crucial roles in protein synthesis and brain neurotransmission. Branched-chain ketoacid dehydrogenase (BCKDH), the flux-generating step of BCAA catabolism, is tightly regulated by reversible phosphorylation of its E1α-subunit. BCKDK is the kinase responsible for the phosphorylation-mediated inactivation of BCKDH. In three siblings with severe developmental delays, microcephaly, autism spectrum disorder and epileptic encephalopathy, we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK. Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced. Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK. Treatment with pharmacological doses of BCAA allowed the restoring of BCAA concentrations and greatly improved seizure control. Behavioral and developmental skills of the patients improved to a lesser extent. Importantly, a retrospective review of the newborn screening results allowed the identification of a strong decrease in BCAA concentrations on dried blood spots, suggesting that BCKDK is a new treatable metabolic disorder probably amenable to newborn screening programs.

Mutations of GABAAR have reportedly led to epileptic encephalopathy and neurodevelopmental disorders. We have identified a novel de novo T292S missense variant of GABRA1 from a pediatric patient with grievous global developmental delay but without obvious epileptic activity. This mutation coincidentally occurs at the same residue as that of a previously reported GABRA1 variant T292I identified from a pediatric patient with severe epilepsy. The distinct phenotypes of these two patients prompted us to compare the impacts of the two mutants on the receptor function and to search for suitable therapeutics. In this study, we used biochemical techniques and patch-clamp recordings in HEK293 cells overexpressing either wild-type or mutated rat recombinant GABAARs. We found that the α1T292S variant significantly increased GABA-evoked whole-cell currents, shifting the dose–response curve to the left without altering the maximal response. In contrast, the α1T292I variant significantly reduced GABA-evoked currents, shifting the dose–response curve to the right with a severely diminished maximum response. Single-channel recordings further revealed that the α1T292S variant increased, while the α1T292I variant decreased the GABAAR single-channel open time and open probability. Importantly, we found that the T292S mutation-induced increase in GABAAR function could be fully normalized by the negative GABAAR modulator thiocolchicoside, whereas the T292I mutation-induced impairment of GABAAR function was largely rescued with a combination of the GABAAR positive modulators diazepam and verapamil. Our study demonstrated that α1T292 is a critical residue for controlling GABAAR channel gating, and mutations at this residue may produce opposite impacts on the function of the receptors. Thus, the present work highlights the importance of functionally characterizing each individual GABAAR mutation for ensuring precision medicine.

Abstract Infantile Spasms, first described by Dr. William West comprises of most severe, resistant, and disabling epileptic encephalopathy along with developmental delay, leaving the patient crippled. It often has a syndromic association warranting a thorough examination of the patient. Astute anesthetic care and vigilance for such a condition is a must for preventing collateral damage during their surgical management. A 3-year-old male, with developmental delay presents with 6–8 episodes of disabling myoclonic seizures with secondary generalization. The seizures are inadequately controlled despite six anti-epileptic medications in the maximum permissible dose and ACTH requiring surgical intervention. Several neck and peripheral joint contractures, associated cardiac and renal anomalies, multiple anti-epileptic medication-associated complications viz deranged liver functions, thrombocytopenia, drug metabolism, and ACTH-related complications impose a mammoth challenge in their peri-operative anesthesia management. It is meritorious to have a detailed understanding of this rare epileptic encephalopathy and an awareness of the bunch of other affiliated conditions to formulate a detailed peri-operative anesthesia management plan. This prevents any form of collateral peri-operative damage and can lead to better outcomes.

Objective:To evaluate the phenotypic spectrum caused by mutations in dynamin 1 (DNM1), encoding the presynaptic protein DNM1, and to investigate possible genotype-phenotype correlations and predicted functional consequences based on structural modeling.Methods:We reviewed phenotypic data of 21 patients (7 previously published) with DNM1 mutations. We compared mutation data to known functional data and undertook biomolecular modeling to assess the effect of the mutations on protein function.Results:We identified 19 patients with de novo mutations in DNM1 and a sibling pair who had an inherited mutation from a mosaic parent. Seven patients (33.3%) carried the recurrent p.Arg237Trp mutation. A common phenotype emerged that included severe to profound intellectual disability and muscular hypotonia in all patients and an epilepsy characterized by infantile spasms in 16 of 21 patients, frequently evolving into Lennox-Gastaut syndrome. Two patients had profound global developmental delay without seizures. In addition, we describe a single patient with normal development before the onset of a catastrophic epilepsy, consistent with febrile infection-related epilepsy syndrome at 4 years. All mutations cluster within the GTPase or middle domains, and structural modeling and existing functional data suggest a dominant-negative effect on DMN1 function.Conclusions:The phenotypic spectrum of DNM1-related encephalopathy is relatively homogeneous, in contrast to many other genetic epilepsies. Up to one-third of patients carry the recurrent p.Arg237Trp variant, which is now one of the most common recurrent variants in epileptic encephalopathies identified to date. Given the predicted dominant-negative mechanism of this mutation, this variant presents a prime target for therapeutic intervention.

BackgroundEarly infantile epileptic encephalopathies are severe disorders consisting of early-onset refractory seizures accompanied often by significant developmental delay. The increasing availability of next-generation sequencing has facilitated the recognition of single gene mutations as an underlying aetiology of some forms of early infantile epileptic encephalopathies.ObjectivesThis study was designed to identify candidate genes as a potential cause of early infantile epileptic encephalopathy, and then to provide genetic and functional evidence supporting patient variants as causative.MethodsWe used whole exome sequencing to identify candidate genes. To model the disease and assess the functional effects of patient variants on candidate protein function, we used in vivo CRISPR/Cas9-mediated genome editing and protein overexpression in frog tadpoles.ResultsWe identified novel de novo variants in neuronal differentiation factor 2 (NEUROD2) in two unrelated children with early infantile epileptic encephalopathy. Depleting neurod2 with CRISPR/Cas9-mediated genome editing induced spontaneous seizures in tadpoles, mimicking the patients’ condition. Overexpression of wild-type NEUROD2 induced ectopic neurons in tadpoles; however, patient variants were markedly less effective, suggesting that both variants are dysfunctional and likely pathogenic.ConclusionThis study provides clinical and functional support for NEUROD2 variants as a cause of early infantile epileptic encephalopathy, the first evidence of human disease caused by NEUROD2 variants.

The X-linked GRIA3 gene encodes the GLUA3 subunit of AMPA-type glutamate receptors. Pathogenic variants in this gene were previously reported in neurodevelopmental diseases, mostly in male patients but rarely in females. Here we report a de novo pathogenic missense variant in GRIA3 (c.1979G>C; p. R660T) identified in a 1-year-old female patient with severe epilepsy and global developmental delay. When exogenously expressed in human embryonic kidney (HEK) cells, GLUA3_R660T showed slower desensitization and deactivation kinetics compared to wildtype (wt) GLUA3 receptors. Substantial non-desensitized currents were observed with the mutant but not for wt GLUA3 with prolonged exposure to glutamate. When co-expressed with GLUA2, the decay kinetics were similarly slowed in GLUA2/A3_R660T with non-desensitized steady state currents. In cultured cerebellar granule neurons, miniature excitatory postsynaptic currents (mEPSCs) were significantly slower in R660T transfected cells than those expressing wt GLUA3. When overexpressed in hippocampal CA1 neurons by in utero electroporation, the evoked EPSCs and mEPSCs were slower in neurons expressing R660T mutant compared to those expressing wt GLUA3. Therefore our study provides functional evidence that a gain of function (GoF) variant in GRIA3 may cause epileptic encephalopathy and global developmental delay in a female subject by enhancing synaptic transmission.

Ataxia is a common clinical feature in inherited metabolic disorders. There are more than 150 inherited metabolic disorders in patients presenting with ataxia in addition to global developmental delay, encephalopathy episodes, a history of developmental regression, coarse facial features, seizures, and other types of movement disorders. Seizures and a history of developmental regression especially are important clinical denominators to consider an underlying inherited metabolic disorder in a patient with ataxia. Some of the inherited metabolic disorders have disease specific treatments to improve outcomes or prevent early death. Early diagnosis and treatment affect positive neurodevelopmental outcomes, so it is important to think of inherited metabolic disorders in the differential diagnosis of ataxia.

Abstract Genetic epilepsies are caused by mutations in a range of different genes, many of them encoding ion channels, receptors or transporters. While the number of detected variants and genes increased dramatically in the recent years, pleiotropic effects have also been recognized, revealing that clinical syndromes with various degrees of severity arise from a single gene, a single mutation, or from different mutations showing similar functional defects. Accordingly, several genes coding for GABAA receptor subunits have been linked to a spectrum of benign to severe epileptic disorders and it was shown that a loss of function presents the major correlated pathomechanism. Here, we identified six variants in GABRA3 encoding the α3-subunit of the GABAA receptor. This gene is located on chromosome Xq28 and has not been previously associated with human disease. Five missense variants and one microduplication were detected in four families and two sporadic cases presenting with a range of epileptic seizure types, a varying degree of intellectual disability and developmental delay, sometimes with dysmorphic features or nystagmus. The variants co-segregated mostly but not completely with the phenotype in the families, indicating in some cases incomplete penetrance, involvement of other genes, or presence of phenocopies. Overall, males were more severely affected and there were three asymptomatic female mutation carriers compared to only one male without a clinical phenotype. X-chromosome inactivation studies could not explain the phenotypic variability in females. Three detected missense variants are localized in the extracellular GABA-binding NH2-terminus, one in the M2-M3 linker and one in the M4 transmembrane segment of the α3-subunit. Functional studies in Xenopus laevis oocytes revealed a variable but significant reduction of GABA-evoked anion currents for all mutants compared to wild-type receptors. The degree of current reduction correlated partially with the phenotype. The microduplication disrupted GABRA3 expression in fibroblasts of the affected patient. In summary, our results reveal that rare loss-of-function variants in GABRA3 increase the risk for a varying combination of epilepsy, intellectual disability/developmental delay and dysmorphic features, presenting in some pedigrees with an X-linked inheritance pattern. 10.1093/brain/awx236_video1 awx236media1 5636589232001

Background: Children with pathogenic variations in SCN8A can present with early infantile epileptic encephalopathy-13, benign familial infantile seizures-5 or intellectual disability alone without epilepsy. In this case series, we discuss six children with variants in SCN8A managed at BC Children’s Hospital. Methods: We describe clinical and genetic results on six individuals with SCN8A variants identified via clinical or research next-generation sequencing. Functional consequences of two SCN8A variants were assessed using electrophysiological analyses in transfected cells. Results: Clinical findings ranged from normal development with well-controlled epilepsy to significant developmental delay with treatment-resistant epilepsy. Phenotypes and genotypes in our cohort are described in the table below. Functional analysis supported gain-of-function in P2 and loss-of-function in P4. Conclusions: Our cohort expands the clinical and genotypic spectrum of SCN8A-related disorders. We establish functional evidence for two missense variants in SCN8A, including LoF variant in a patient with intellectual disability, and autism spectrum disorder without seizures.

The CACNA1G gene encodes the low-voltage-activated Cav3.1 channel, which is expressed in various areas of the CNS, including the cerebellum. We studied two missense CACNA1G variants, p.L208P and p.L909F, and evaluated the relationships between the severity of Cav3.1 dysfunction and the clinical phenotype. The presentation was of a developmental and epileptic encephalopathy without evident cerebellar atrophy. Both patients exhibited axial hypotonia, developmental delay, and severe to profound cognitive impairment. The patient with the L909F mutation had initially refractory seizures and cerebellar ataxia, whereas the L208P patient had seizures only transiently but was overall more severely affected. In transfected mammalian cells, we determined the biophysical characteristics of L208P and L909F variants, relative to the wild-type channel and a previously reported gain-of-function Cav3.1 variant. The L208P mutation shifted the activation and inactivation curves to the hyperpolarized direction, slowed the kinetics of inactivation and deactivation, and reduced the availability of Ca2+ current during repetitive stimuli. The L909F mutation impacted channel function less severely, resulting in a hyperpolarizing shift of the activation curve and slower deactivation. These data suggest that L909F results in gain-of-function, whereas L208P exhibits mixed gain-of-function and loss-of-function effects due to opposing changes in the biophysical properties. Our study expands the clinical spectrum associated with CACNA1G mutations, corroborating further the causal association with distinct complex phenotypes.

Background: Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit beta (PIK3CB) is a member of the PI3K complex. This complex has two p110 members; PIK3CA (p110a) and PIK3CB (p110b) which are both ubiquitously expressed. PI3K complex functions to phosphorylate PIP2 to PIP3 which activates AKT and subsequently mTOR. PIK3CA mutations have been previously linked with macrocephaly and developmental delay. Methods: An 18 month old girl was investigated for severe hypotonia, developmental delay and macrocephaly. Head circumference was >97%ile at birth and 53.0 cm (>99%ile, +5.4 SD) at 13 months old. She had no hydrocephalus or epilepsy. MRI brain (18 months old) re-identified megalencephaly and diffuse polymicrogyria. Symmetric signal abnormality was noted in the periventricular white matter, unchanged between 8 and 18 month images. MR spectroscopy was unrevealing. At 18 months she remains unable to sit independently. Exome sequencing was performed and functional studies to further support variant pathogenicity. Results: Exome sequencing identified de novo variant in PIK3CB: c.1735G>T; p.Asp579Tyr. No mutations were noted in other genes known to cause developmental delay, macrocephaly or overgrowth syndromes. Functional studies in patient cells showed dysregulation of PIK3CB and downstream signalling, providing support for causality of this novel disease gene. Conclusions: We believe that our patient’s macrocephaly (+5.4 SD) and diffuse polymicrogyria results from altered PIK3CB function.

Background: Patients with DNM1-encephalopathy almost exclusively have missense variants, mostly in the GTPase domain of DNM1. Delayed myelination has been reported in at least three patients with DNM1-encephalopathy, all with missense mutations in the DNM1 central domain. Only one DNM1 splice-site variant has previously been reported, and the authors questioned whether the variant accounted for all aspects of the patient’s phenotype. Methods: Case-Report. Results: Our patient had hypotonia and brief multifocal tonic seizures from age-1-month. He still has profound global developmental delay, daily seizures and microcephaly. MRI-Brain at age-21-months showed T2 hyperintensity in the bilateral periventricular and subcortical white matter; spectroscopy showed a questionable lactate peak and an elevated choline peak relative to N-acetylaspartate. Clinical gene-panel identified a heterozygous de novo pathogenic variant in intron 9 of DNM1 (c.1197-8G > A; IVS9- 8G>A). In-silico tools categorized this variant as deleterious secondary to a splicing defect. RT-PCR analysis on peripheral blood was unsuccessful as DNM1 expression is extremely low outside of the brain. Conclusions: Our patient carried the same DNM1 variant previously reported, indicating this is a recurrent pathogenic splice-site variant. The spectroscopic abnormalities suggest a possible element of demyelination in DNM1 variants of the central domain, though the mechanism remains unclear.

AbstractDevelopmental and/or epileptic encephalopathies (DEEs) are a group of devastating genetic disorders, resulting in early-onset, therapy-resistant seizures and developmental delay. Here we report on 22 individuals from 15 families presenting with a severe form of intractable epilepsy, severe developmental delay, progressive microcephaly, visual disturbance and similar minor dysmorphisms. Whole exome sequencing identified a recurrent, homozygous variant (chr2:64083454A > G) in the essential UDP-glucose pyrophosphorylase (UGP2) gene in all probands. This rare variant results in a tolerable Met12Val missense change of the longer UGP2 protein isoform but causes a disruption of the start codon of the shorter isoform, which is predominant in brain. We show that the absence of the shorter isoform leads to a reduction of functional UGP2 enzyme in neural stem cells, leading to altered glycogen metabolism, upregulated unfolded protein response and premature neuronal differentiation, as modeled during pluripotent stem cell differentiation in vitro. In contrast, the complete lack of all UGP2 isoforms leads to differentiation defects in multiple lineages in human cells. Reduced expression of Ugp2a/Ugp2b in vivo in zebrafish mimics visual disturbance and mutant animals show a behavioral phenotype. Our study identifies a recurrent start codon mutation in UGP2 as a cause of a novel autosomal recessive DEE syndrome. Importantly, it also shows that isoform-specific start-loss mutations causing expression loss of a tissue-relevant isoform of an essential protein can cause a genetic disease, even when an organism-wide protein absence is incompatible with life. We provide additional examples where a similar disease mechanism applies.

Individuals with mutations in forkhead box G1 (FOXG1) belong to a distinct clinical entity, termed “FOXG1-related encephalopathy”. There are two clinical phenotypes/syndromes identified in FOXG1-related encephalopathy, duplications and deletions/intragenic mutations. In children with deletions or intragenic mutations of FOXG1, the recognized clinical features include microcephaly, developmental delay, severe cognitive disabilities, early-onset dyskinesia and hyperkinetic movements, stereotypies, epilepsy, and cerebral malformation. In contrast, children with duplications of FOXG1 are typically normocephalic and have normal brain magnetic resonance imaging. They also have different clinical characteristics in terms of epilepsy, movement disorders, and neurodevelopment compared with children with deletions or intragenic mutations. FOXG1 is a transcriptional factor. It is expressed mainly in the telencephalon and plays a pleiotropic role in the development of the brain. It is a key player in development and territorial specification of the anterior brain. In addition, it maintains the expansion of the neural proliferating pool, and also regulates the pace of neocortical neuronogenic progression. It also facilitates cortical layer and corpus callosum formation. Furthermore, it promotes dendrite elongation and maintains neural plasticity, including dendritic arborization and spine densities in mature neurons. In this review, we summarize the clinical features, molecular genetics, and possible pathogenesis of FOXG1-related syndrome.

Objective:To determine the functional effect of SCN8A missense mutations in 2 children with intellectual disability and developmental delay but no seizures.Methods:Genomic DNA was analyzed by next-generation sequencing. SCN8A variants were introduced into the Nav1.6 complementary DNA by site-directed mutagenesis. Channel activity was measured electrophysiologically in transfected ND7/23 cells. The stability of the mutant channels was assessed by Western blot.Results:Both children were heterozygous for novel missense variants that altered conserved residues in transmembrane segments of Nav1.6, p.Gly964Arg in D2S6 and p.Glu1218Lys in D3S1. Both altered amino acids are evolutionarily conserved in vertebrate and invertebrate channels and are predicted to be deleterious. Neither was observed in the general population. Both variants completely prevented the generation of sodium currents in transfected cells. The abundance of Nav1.6 protein was reduced by the Glu1218Lys substitution.Conclusions:Haploinsufficiency of SCN8A is associated with cognitive impairment. These observations extend the phenotypic spectrum of SCN8A mutations beyond their established role in epileptic encephalopathy (OMIM#614558) and other seizure disorders. SCN8A should be considered as a candidate gene for intellectual disability, regardless of seizure status.

Abstract3-MEthylGlutaconic aciduria, Deafness, Encephalopathy, neuroradiological evidence of Leigh-like disease (MEGDEL syndrome) was initially described in four children with additional features of defective oxidative phosphorylation. Loss of functional variants in the SERAC1 gene was later reported in relation with this disorder of phospholipid remodeling. We describe a girl born after a pregnancy complicated by intrauterine growth retardation. In the neonatal period, she presented hypotonia, lethargy, weak reflexes, transient hypoglycemia, and elevated transaminases. Magnetic resonance imaging (MRI) performed at 12 days of life showed bilateral basal ganglia alterations suggestive of Leigh syndrome. She progressed with failure to thrive, severe delay of developmental milestones, axial hypotonia, spastic tetraparesis and dystonic movements. Investigations disclosed hyperlactacidemia, and the urinary organic acids revealed high levels mainly of 3-methylglutaconic acid. Muscle biopsy showed decreased activity of several complexes of the respiratory chain. Compound heterozygosity for two previously unreported variants in SERAC1 leads to the diagnosis of MEGDEL syndrome. Unlike other patients, this child presents very early MRI alterations and manifests no deafness.

A five-year-old girl presented with headache attacks, clumsiness, and a history of transient gait disturbances. She and her father, mother, twin sister, and brother underwent neurological evaluation, neuroimaging, and exome sequencing covering 357 genes associated with movement disorders. Sequencing revealed the new variant KCND3 c.838G>A, p.E280K in the father and sisters, but not in the mother and brother. KCND3 encodes voltage-gated potassium channel D3 (Kv4.3) and mutations have been associated with spinocerebellar ataxia type 19/22 (SCA19/22) and cardiac arrhythmias. SCA19/22 is characterized by ataxia, Parkinsonism, peripheral neuropathy, and sometimes, intellectual disability. Neuroimaging, EEG, and ECG were unremarkable. Mild developmental delay with impaired fluid reasoning was observed in both sisters, but not in the brother. None of the family members demonstrated ataxia or parkinsonism. In Xenopus oocyte electrophysiology experiments, E280K was associated with a rightward shift in the Kv4.3 voltage-activation relationship of 11 mV for WT/E280K and +17 mV for E280K/E280K relative to WT/WT. Steady-state inactivation was similarly right-shifted. Maximal peak current amplitudes were similar for WT/WT, WT/E280K, and E280K/E280K. Our data indicate that Kv4.3 E280K affects channel activation and inactivation and is associated with developmental delay. However, E280K appears to be relatively benign considering it does not result in overt ataxia.

Epileptic encephalopathies (EE) are severe epilepsy syndromes characterized by multiple seizure types, developmental delay and even regression. This class of disorders are increasingly being identified as resulting from de novo genetic mutations including many identified mutations in the family of chromodomain helicase DNA binding (CHD) proteins. In particular, several de novo pathogenic mutations have been identified in the gene encoding chromodomain helicase DNA binding protein 2 (CHD2), a member of the sucrose nonfermenting (SNF-2) protein family of epigenetic regulators. These mutations in the CHD2 gene are causative of early onset epileptic encephalopathy, abnormal brain function, and intellectual disability. Our understanding of the mechanisms by which modification or loss of CHD2 cause this condition remains poorly understood. Here, we review what is known and still to be elucidated as regards the structure and function of CHD2 and how its dysregulation leads to a highly variable range of phenotypic presentations.

Epileptic encephalopathies (EE) are severe epilepsy syndromes characterized by multiple seizure types, developmental delay and even regression. This class of disorders are increasingly being identified as resulting from de novo genetic mutations including many identified mutations in the family of chromodomain helicase DNA binding (CHD) proteins. In particular, several de novo pathogenic mutations have been identified in the gene encoding chromodomain helicase DNA binding protein 2 (CHD2), a member of the sucrose nonfermenting (SNF-2) protein family of epigenetic regulators. These mutations in the CHD2 gene are causative of early onset epileptic encephalopathy, abnormal brain function, and intellectual disability. Our understanding of the mechanisms by which modification or loss of CHD2 cause this condition remains poorly understood. Here, we review what is known and still to be elucidated as regards the structure and function of CHD2 and how its dysregulation leads to a highly variable range of phenotypic presentations.

BackgroundThe combination of febrile illness-induced encephalopathy and rhabdomyolysis has thus far only been described in disorders that affect cellular energy status. In the absence of specific metabolic abnormalities, diagnosis can be challenging.ObjectiveThe objective of this study was to identify and characterise pathogenic variants in two individuals from unrelated families, both of whom presented clinically with a similar phenotype that included neurodevelopmental delay, febrile illness-induced encephalopathy and episodes of rhabdomyolysis, followed by developmental arrest, epilepsy and tetraplegia.MethodsWhole exome sequencing was used to identify pathogenic variants in the two individuals. Biochemical and cell biological analyses were performed on fibroblasts from these individuals and a yeast two-hybrid analysis was used to assess protein-protein interactions.ResultsProbands shared a homozygous TRAPPC2L variant (c.109G>T) resulting in a p.Asp37Tyr missense variant. TRAPPC2L is a component of transport protein particle (TRAPP), a group of multisubunit complexes that function in membrane traffic and autophagy. Studies in patient fibroblasts as well as in a yeast system showed that the p.Asp37Tyr protein was present but not functional and resulted in specific membrane trafficking delays. The human missense mutation and the analogous mutation in the yeast homologue Tca17 ablated the interaction between TRAPPC2L and TRAPPC10/Trs130, a component of the TRAPP II complex. Since TRAPP II activates the GTPase RAB11, we examined the activation state of this protein and found increased levels of the active RAB, correlating with changes in its cellular morphology.ConclusionsOur study implicates a RAB11 pathway in the aetiology of the TRAPPC2L disorder and has implications for other TRAPP-related disorders with similar phenotypes.

Purpose Functional brain imaging is playing an increasingly important role in the diagnosis and treatment of communication disorders, yet many populations and settings are incompatible with functional magnetic resonance imaging and other commonly used techniques. We conducted a systematic review of neuroimaging studies using functional near-infrared spectroscopy (fNIRS) with individuals with speech or language impairment across the life span. We aimed to answer the following question: To what extent has fNIRS been used to investigate the neural correlates of speech-language impairment? Method This systematic review was preregistered with PROSPERO, the international prospective register of systematic reviews (CRD42019136464). We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol for preferred reporting items for systematic reviews. The database searches were conducted between February and March of 2019 with the following search terms: (a) fNIRS or functional near-infrared spectroscopy or NIRS or near-infrared spectroscopy, (b) speech or language, and (c) disorder or impairment or delay. Results We found 34 fNIRS studies that involved individuals with speech or language impairment across nine categories: (a) autism spectrum disorders; (b) developmental speech and language disorders; (c) cochlear implantation and deafness; (d) dementia, dementia of the Alzheimer's type, and mild cognitive impairment; (e) locked-in syndrome; (f) neurologic speech disorders/dysarthria; (g) stroke/aphasia; (h) stuttering; and (i) traumatic brain injury. Conclusions Though it is not without inherent challenges, fNIRS may have advantages over other neuroimaging techniques in the areas of speech and language impairment. fNIRS has clinical applications that may lead to improved early and differential diagnosis, increase our understanding of response to treatment, improve neuroprosthetic functioning, and advance neurofeedback.

Pathogenic variants in KCNA2, encoding for the voltage-gated potassium channel Kv1.2, have been identified as the cause for an evolving spectrum of neurological disorders. Affected individuals show early-onset developmental and epileptic encephalopathy, intellectual disability, and movement disorders resulting from cerebellar dysfunction. In addition, individuals with a milder course of epilepsy, complicated hereditary spastic paraplegia, and episodic ataxia have been reported. By analyzing phenotypic, functional, and genetic data from published reports and novel cases, we refine and further delineate phenotypic as well as functional subgroups of KCNA2-associated disorders. Carriers of variants, leading to complex and mixed channel dysfunction that are associated with a gain- and loss-of-potassium conductance, more often show early developmental abnormalities and an earlier onset of epilepsy compared to individuals with variants resulting in loss- or gain-of-function. We describe seven additional individuals harboring three known and the novel KCNA2 variants p.(Pro407Ala) and p.(Tyr417Cys). The location of variants reported here highlights the importance of the proline(405)–valine(406)–proline(407) (PVP) motif in transmembrane domain S6 as a mutational hotspot. A novel case of self-limited infantile seizures suggests a continuous clinical spectrum of KCNA2-related disorders. Our study provides further insights into the clinical spectrum, genotype–phenotype correlation, variability, and predicted functional impact of KCNA2 variants.

Introduction: The optimal method to detect impairments in cerebrovascular pressure autoregulation in neonates with hypoxic-ischemic encephalopathy (HIE) is unclear. Improving autoregulation monitoring methods would significantly advance neonatal neurocritical care. Methods: We tested several mathematical algorithms from the frequency and time domains in a piglet model of HIE, hypothermia, and hypotension. We used laser Doppler flowmetry and induced hypotension to delineate the gold standard lower limit of autoregulation (LLA). Receiver operating characteristics curve analyses were used to determine which indices could distinguish blood pressure above the LLA from that below the LLA in each piglet. Results: Phase calculation in the frequency band with maximum coherence, as well as the correlation between mean arterial pressure (MAP) and near-infrared spectroscopy relative total tissue hemoglobin (HbT) or regional oxygen saturation (rSO2), accurately discriminated functional from dysfunctional autoregulation. Neither hypoxia-ischemia nor hypothermia affected the accuracy of these indices. Coherence alone and gain had low diagnostic value relative to phase and correlation. Conclusion: Our findings indicate that phase shift is the most accurate component of autoregulation monitoring in the developing brain, and it can be measured using correlation or by calculating phase when coherence is maximal. Phase and correlation autoregulation indices from MAP and rSO2 and vasoreactivity indices from MAP and HbT are accurate metrics that are suitable for clinical HIE studies.

Kv7.2 subunits encoded by the KCNQ2 gene provide a major contribution to the M-current (IKM), a voltage-gated K+ current crucially involved in the regulation of neuronal excitability. Heterozygous missense variants in Kv7.2 are responsible for epileptic diseases characterized by highly heterogeneous genetic transmission and clinical severity, ranging from autosomal-dominant Benign Familial Neonatal Seizures (BFNS) to sporadic cases of severe epileptic and developmental encephalopathy (DEE). Here, we describe a patient with neonatal onset DEE, carrying a previously undescribed heterozygous KCNQ2 c.418G > C, p.Glu140Gln (E140Q) variant. Patch-clamp recordings in CHO cells expressing the E140Q mutation reveal dramatic loss of function (LoF) effects. Multistate structural modelling suggested that the E140Q substitution impeded an intrasubunit electrostatic interaction occurring between the E140 side chain in S2 and the arginine at position 210 in S4 (R210); this interaction is critically involved in stabilizing the activated configuration of the voltage-sensing domain (VSD) of Kv7.2. Functional results from coupled charge reversal or disulfide trapping experiments supported such a hypothesis. Finally, retigabine restored mutation-induced functional changes, reinforcing the rationale for the clinical use of Kv7 activators as personalized therapy for DEE-affected patients carrying Kv7.2 LoF mutations.

Mutations in the SZT2 gene have been associated with developmental and epileptic encephalopathy-18, a rare severe autosomal recessive neurologic disorder, characterized by psychomotor impairment/intellectual disability, dysmorphic facial features and early onset of refractory seizures. Here we report the generation of the first induced pluripotent stem cell (iPSC) lines from a patient with treatment-resistant epilepsy, carrying compound heterozygous mutations in SZT2 (Mut1: c.498G>T and Mut2: c.6553C>T), and his healthy heterozygous parents. Peripheral blood mononuclear cells were reprogrammed by a non-integrating Sendai virus-based reprogramming system. The generated human iPSC lines exhibited expression of the main pluripotency markers, the potential to differentiate into all three germ layers and presented a normal karyotype. These lines represent a valuable resource to study neurodevelopmental alterations, and to obtain mature, pathology-relevant neuronal populations as an in vitro model to perform functional assays and test the patient’s responsiveness to novel antiepileptic treatments.

SLC25A36 is a pyrimidine nucleotide carrier playing an important role in maintaining mitochondrial biogenesis. Deficiencies in SLC25A36 in mouse embryonic stem cells have been associated with mtDNA depletion as well as mitochondrial dysfunction. In human beings, diseases triggered by SLC25A36 mutations have not been described yet. We report the first known case of SLC25A36 deficiency in a 12-year-old patient with hypothyroidism, hyperinsulinism, hyperammonemia, chronical obstipation, short stature, along with language and general developmental delay. Whole exome analysis identified the homozygous mutation c.803dupT, p.Ser269llefs*35 in the SLC25A36 gene. Functional analysis of mutant SLC25A36 protein in proteoliposomes showed a virtually abolished transport activity. Immunoblotting results suggest that the mutant SLC25A36 protein in the patient undergoes fast degradation. Supplementation with oral uridine led to an improvement of thyroid function and obstipation, increase of growth and developmental progress. Our findings suggest an important role of SLC25A36 in hormonal regulations and oral uridine as a safe and effective treatment.

GLUT1 deficiency syndrome (GLUT1DS1; OMIM #606777) is a rare genetic metabolic disease, characterized by infantile-onset epileptic encephalopathy, global developmental delay, progressive microcephaly, and movement disorders (e.g., spasticity and dystonia). It is caused by heterozygous mutations in the SLC2A1 gene, which encodes the GLUT1 protein, a glucose transporter across the blood-brain barrier (BBB). Most commonly, these variants arise de novo resulting in sporadic cases, although several familial cases with AD inheritance pattern have been described. Twenty-seven Italian pediatric patients, clinically suspect of GLUT1DS from both sporadic and familial cases, have been enrolled. We detected by trios sequencing analysis 25 different variants causing GLUT1DS. Of these, 40% of the identified variants (10 out of 25) had never been reported before, including missense, frameshift, and splice site variants. Their structural mapping on the X-ray structure of GLUT1 strongly suggested the potential pathogenic effects of these novel disease-related mutations, broadening the genotypic spectrum heterogeneity found in the SLC2A1 gene. Moreover, 24% is located in a vulnerable region of the GLUT1 protein that involves transmembrane 4 and 5 helices encoded by exon 4, confirming a mutational hotspot in the SLC2A1 gene. Lastly, we investigated possible correlations between mutation type and clinical and biochemical data observed in our GLUT1DS cohort, revealing that splice site and frameshift variants are related to a more severe phenotype and low CSF parameters.

Abstract Mitochondria undergo continuous cycles of fusion and fission in response to physiopathological stimuli. The key player in mitochondrial fission is dynamin-related protein 1 (DRP1), a cytosolic protein encoded by dynamin 1-like (DNM1L) gene, which relocalizes to the outer mitochondrial membrane, where it assembles, oligomerizes and drives mitochondrial division upon guanosine-5′-triphosphate (GTP) hydrolysis. Few DRP1 mutations have been described so far, with patients showing complex and variable phenotype ranging from early death to encephalopathy and/or optic atrophy. The disease is the consequence of defective mitochondrial fission due to faulty DRP1 function. However, the underlying molecular mechanisms and the functional consequences at mitochondrial and cellular level remain elusive. Here we report on a 5-year-old girl presenting psychomotor developmental delay, global hypotonia and severe ataxia due to axonal sensory neuropathy harboring a novel de novo heterozygous missense mutation in the GTPase domain of DRP1 (NM_012062.3:c.436G>A, NP_036192.2: p.D146N variant in DNM1L). Patient’s fibroblasts show hyperfused/balloon-like giant mitochondria, highlighting the importance of D146 residue for DRP1 function. This dramatic mitochondrial rearrangement phenocopies what observed overexpressing DRP1-K38A, a well-known experimental dominant negative version of DRP1. In addition, we demonstrated that p.D146N mutation has great impact on peroxisomal shape and function. The p.D146N mutation compromises the GTPase activity without perturbing DRP1 recruitment or assembly, causing decreased mitochondrial and peroxisomal turnover. In conclusion, our findings highlight the importance of sensory neuropathy in the clinical spectrum of DRP1 variants and, for the first time, the impact of DRP1 mutations on mitochondrial turnover and peroxisomal functionality.

The CACNA1A gene encodes the pore-forming α1A subunit of the voltage-gated CaV2.1 Ca2+ channel, essential in neurotransmission, especially in Purkinje cells. Mutations in CACNA1A result in great clinical heterogeneity with progressive symptoms, paroxysmal events or both. During infancy, clinical and neuroimaging findings may be unspecific, and no dysmorphic features have been reported. We present the clinical, radiological and evolutionary features of three patients with congenital ataxia, one of them carrying a new variant. We report the structural localization of variants and their expected functional consequences. There was an improvement in cerebellar syndrome over time despite a cerebellar atrophy progression, inconsistent response to acetazolamide and positive response to methylphenidate. The patients shared distinctive facial gestalt: oval face, prominent forehead, hypertelorism, downslanting palpebral fissures and narrow nasal bridge. The two α1A affected residues are fully conserved throughout evolution and among the whole human CaV channel family. They contribute to the channel pore and the voltage sensor segment. According to structural data analysis and available functional characterization, they are expected to exert gain- (F1394L) and loss-of-function (R1664Q/R1669Q) effect, respectively. Among the CACNA1A-related phenotypes, our results suggest that non-progressive congenital ataxia is associated with developmental delay and dysmorphic features, constituting a recognizable syndromic neurodevelopmental disorder.

Gamma-aminobutyric acid (GABA) transaminase—also called GABA aminotransferase (GABA-AT)—deficiency is a rare autosomal recessive disorder characterized by a severe neonatal-infantile epileptic encephalopathy with symptoms such as seizures, hypotonia, hyperreflexia, developmental delay, and growth acceleration. GABA transaminase deficiency is caused by mutations in GABA-AT, the enzyme responsible for the catabolism of GABA. Mutations in multiple locations on GABA-AT have been reported and their locations have been shown to influence the onset of the disease and the severity of symptoms. We examined how GABA-AT mutations influence the structural stability of the enzyme and GABA-binding affinity using computational methodologies such as molecular dynamics simulation and binding free energy calculation to understand the underlying mechanism through which GABA-AT mutations cause GABA-AT deficiency. GABA-AT 3D model depiction was carried out together with seven individual mutated models of GABA-AT. The structural stability of all the predicted models was analyzed using several tools and web servers. All models were evaluated based on their phytochemical values. Additionally, 100 ns MD simulation was carried out and the mutated models were evaluated using RMSD, RMSF, Rg, and SASA. gmxMMPBSA free energy calculation was carried out. Moreover, RMSD and free energy calculations were also compared with those obtained using online web servers. Our study demonstrates that P152S, Q296H, and R92Q play a more critical role in the structural instability of GABA-AT compared with the other mutated models: G465R, L211F, L478P, and R220K.

Early infantile epileptic encephalopathy (EIEE) is a severe neurologic and neurodevelopmental disease that manifests in the first year of life. It shows a high degree of genetic heterogeneity, but the genetic origin is only identified in half of the cases. We report the case of a female child initially diagnosed with Leber congenital amaurosis (LCA), an early-onset retinal dystrophy due to photoreceptor cell degeneration in the retina. The first examination at 9 months of age revealed no reaction to light or objects and showed wandering eye movements. Ophthalmological examination did not show any ocular abnormalities. The patient displayed mildly dysmorphic features and a global developmental delay. Brain MRI demonstrated pontine hypo-/dysplasia. The patient developed myoclonic epileptic seizures and epileptic spasms with focal and generalized epileptiform discharges on electroencephalogram (EEG) at the age of 16 months. Genetic screening for a potentially pathogenic DNA sequence variant by whole-exome sequencing (WES) revealed a novel, conserved, homozygous frameshift variant (c.5391delA, p.(Ala1798LeufsTer59)) in exon 42 of the DOCK7 gene (NM_001271999.1). Further analysis by SNP array (Karyomapping) showed loss of heterozygosity (LOH) in four segments of chromosome 1. WES data of the parents and the index patient (trio analysis) demonstrated that chromosome 1 was exclusively inherited from the mother. Four LOH segments of chromosome 1 alternately showed isodisomy (UPiD) and heterodisomy (UPhD). In WES data, the father was a noncarrier, and the mother was heterozygous for this DOCK7 variant. The DOCK7 gene is located in 1p31.3, a region situated in one of the four isodisomic segments of chromosome 1, explaining the homozygosity seen in the affected child. Finally, Sanger sequencing confirmed maternal UPiD for the DOCK7 variant. Homozygous or compound heterozygous pathogenic variants in the DOCK7 (dedicator of cytokinesis 7) gene are associated with autosomal recessive, early infantile epileptic encephalopathy 23 (EIEE23; OMIM #615,859), a rare and heterogeneous group of neurodevelopmental disorders diagnosed during early childhood. To our knowledge, this is the first report of segmental uniparental iso- and heterodisomy of chromosome 1, leading to homozygosity of the DOCK7 frameshift variant in the affected patient.

The postsynaptic density (PSD) is a massive protein complex, critical for synaptic strength and plasticity in excitatory neurons. Here, the scaffolding protein PSD-95 plays a crucial role as it organizes key PSD components essential for synaptic signaling, development, and survival. Recently, variants in DLG4 encoding PSD-95 were found to cause a neurodevelopmental disorder with a variety of clinical features including intellectual disability, developmental delay, and epilepsy. Genetic variants in several of the interaction partners of PSD-95 are associated with similar phenotypes, suggesting that deficient PSD-95 may affect the interaction partners, explaining the overlapping symptoms. Here, we review the transmembrane interaction partners of PSD-95 and their association with neurodevelopmental disorders. We assess how the structural changes induced by DLG4 missense variants may disrupt or alter such protein–protein interactions, and we argue that the pathological effect of DLG4 variants is, at least partly, exerted indirectly through interaction partners of PSD-95. This review presents a direction for functional studies to elucidate the pathogenic mechanism of deficient PSD-95, providing clues for therapeutic strategies.

JARID2 (Jumonji, AT-rich interactive domain 2) haploinsufficiency is associated with a clinically distinct neurodevelopmental syndrome. It is characterized by intellectual disability, developmental delay, autistic features, behavior abnormalities, cognitive impairment, hypotonia, and dysmorphic features. JARID2 acts as a transcriptional repressor protein that is involved in the regulation of histone methyltransferase complexes. JARID2 plays a role in the epigenetic machinery, and the associated syndrome has an identified DNA methylation episignature derived from sequence variants and intragenic deletions involving JARID2. For this study, our aim was to determine whether patients with larger deletions spanning beyond JARID2 present a similar DNA methylation episignature and to define the critical region involved in aberrant DNA methylation in 6p22–p24 microdeletions. We examined the DNA methylation profiles of peripheral blood from 56 control subjects, 13 patients with (likely) pathogenic JARID2 variants or patients carrying copy number variants, and three patients with JARID2 VUS variants. The analysis showed a distinct and strong differentiation between patients with (likely) pathogenic variants, both sequence and copy number, and controls. Using the identified episignature, we developed a binary model to classify patients with the JARID2-neurodevelopmental syndrome. DNA methylation analysis indicated that JARID2 is the driver gene for aberrant DNA methylation observed in 6p22–p24 microdeletions. In addition, we performed analysis of functional correlation of the JARID2 genome-wide methylation profile with the DNA methylation profiles of 56 additional neurodevelopmental disorders. To conclude, we refined the critical region for the presence of the JARID2 episignature in 6p22–p24 microdeletions and provide insight into the functional changes in the epigenome observed when regulation by JARID2 is lost.

FAM20C (family with sequence similarity 20, member C) is a serine/threonine-specific protein kinase that is ubiquitously expressed and mainly associated with biomineralization and phosphatemia regulation. It is mostly known due to pathogenic variants causing its deficiency, which results in Raine syndrome (RNS), a sclerosing bone dysplasia with hypophosphatemia. The phenotype is recognized by the skeletal features, which are related to hypophosphorylation of different FAM20C bone-target proteins. However, FAM20C has many targets, including brain proteins and the cerebrospinal fluid phosphoproteome. Individuals with RNS can have developmental delay, intellectual disability, seizures, and structural brain defects, but little is known about FAM20C brain-target-protein dysregulation or about a potential pathogenesis associated with neurologic features. In order to identify the potential FAM20C actions on the brain, an in silico analysis was conducted. Structural and functional defects reported in RNS were described; FAM20C targets and interactors were identified, including their brain expression. Gene ontology of molecular processes, function, and components was completed for these targets, as well as for potential involved signaling pathways and diseases. The BioGRID and Human Protein Atlas databases, the Gorilla tool, and the PANTHER and DisGeNET databases were used. Results show that genes with high expression in the brain are involved in cholesterol and lipoprotein processes, plus axo-dendritic transport and the neuron part. These results could highlight some proteins involved in the neurologic pathogenesis of RNS.

The nuclear thyroid hormone receptors (THRs) are key mediators of thyroid hormone function on the cellular level via modulation of gene expression. Two different genes encode THRs (THRA and THRB), and are pleiotropically involved in development, metabolism, and growth. The THRA1 and THRA2 isoforms, which result from alternative splicing of THRA, differ in their C-terminal ligand-binding domain (LBD). Most published disease-associated THRA variants are located in the LBD of THRA1 and impede triiodothyronine (T3) binding. This keeps the nuclear receptor in an inactive state and inhibits target gene expression. Here, we investigated a new dominant THRA variant (chr17:g.38,241,010A > G, GRCh37.13 | c.518A > G, NM_199334 | p.(E173G), NP_955366), which is located between the DNA- and ligand-binding domains and affects both splicing isoforms. Patients presented partially with hypothyroid (intellectual disability, motor developmental delay, brain atrophy, and constipation) and partially with hyperthyroid symptoms (tachycardia and behavioral abnormalities) to varying degrees. Functional characterization of THRA1p.(E173G) by reporter gene assays revealed increased transcriptional activity in contrast to THRA1(WT), unexpectedly revealing the first gain-of-function mutation found in THRA1. The THRA2 isoform does not bind T3 and antagonizes THRA1 action. Introduction of p.(E173G) into THRA2 increased its inhibitory effect on THRA1, which helps to explain the hypothyroid symptoms seen in our patients. We used protein structure models to investigate possible underlying pathomechanisms of this variant with a gain-of-antagonistic function and suggest that the p.(E173G) variant may have an influence on the dimerization domain of the nuclear receptor.

Aromatic amino acid decarboxylase (AADC) deficiency is a rare monogenic disease due to mutations in the ddc gene producing AADC, a homodimeric pyridoxal 5′-phosphate-dependent enzyme. The disorder is often fatal in the first decade and is characterized by profound motor impairments and developmental delay. In the last two years, there has been a net rise in the number of patients and variants identified, maybe also pushed by the ongoing gene therapy trials. The majority of the identified genotypes are compound heterozygous (about 70%). Efforts are underway to reach early diagnosis, find possible new markers/new fast methods, and predict clinical outcome. However, no clear correlation of genotype-to-phenotype exists to date. Nevertheless, for homozygous patients, reliable results have been obtained using genetic methods combined with available computational tools on crystal structures corroborated by biochemical investigations on recombinant homodimeric AADC variants that have been obtained and characterized in solution. For these variants, the molecular basis for the defect has been suggested and validated, since it correlates quite well with mildness/severity of the homozygous phenotype. Instead, prediction for compound heterozygous patients is more difficult since complementation effects could happen. Here, by analyzing the existing literature on compound heterozygosity in AADC deficiency and other genetic disorders, we highlight that, in order to assess pathogenicity, the measurement of activity of the AADC heterodimeric variant should be integrated by bioinformatic, structural, and functional data on the whole protein constellation theoretically present in such patients. A wider discussion on symptomatic heterozygosity in AADC deficiency is also presented.

The 15q11.2 BP1-BP2 deletion (Burnside-Butler) syndrome is emerging as the most common cytogenetic finding in patients with neurodevelopmental or autism spectrum disorders (ASD) presenting for microarray genetic testing. Clinical findings in Burnside-Butler syndrome include developmental and motor delays, congenital abnormalities, learning and behavioral problems, and abnormal brain findings. To better define symptom presentation, we performed comprehensive cognitive and behavioral testing, collected medical and family histories, and conducted clinical genetic evaluations. The 15q11.2 BP1-BP2 region includes the TUBGCP5, CYFIP1, NIPA1, and NIPA2 genes. To determine if additional genomic variation outside of the 15q11.2 region influences expression of symptoms in Burnside-Butler syndrome, whole-exome sequencing was performed on the parents and affected children for the first time in five families with at least one parent and child with the 15q1l.2 BP1-BP2 deletion. In total, there were 453 genes with possibly damaging variants identified across all of the affected children. Of these, 99 genes had exclusively de novo variants and 107 had variants inherited exclusively from the parent without the deletion. There were three genes (APBB1, GOLGA2, and MEOX1) with de novo variants that encode proteins evidenced to interact with CYFIP1. In addition, one other gene of interest (FAT3) had variants inherited from the parent without the deletion and encoded a protein interacting with CYFIP1. The affected individuals commonly displayed a neurodevelopmental phenotype including ASD, speech delay, abnormal reflexes, and coordination issues along with craniofacial findings and orthopedic-related connective tissue problems. Of the 453 genes with variants, 35 were associated with ASD. On average, each affected child had variants in 6 distinct ASD-associated genes (x¯ = 6.33, sd = 3.01). In addition, 32 genes with variants were included on clinical testing panels from Clinical Laboratory Improvement Amendments (CLIA) approved and accredited commercial laboratories reflecting other observed phenotypes. Notably, the dataset analyzed in this study was small and reported results will require validation in larger samples as well as functional follow-up. Regardless, we anticipate that results from our study will inform future research into the genetic factors influencing diverse symptoms in patients with Burnside-Butler syndrome, an emerging disorder with a neurodevelopmental behavioral phenotype.

<p><strong>List of abstracts and authors:</strong></p><p><strong>1. Bipolar disorder not otherwise specified -overdiagnosed or underdiagnosed?</strong></p><p>E Allers</p><p><strong>2. The prognosis of major depression untreated and treated: Does the data reflect the true picture of the prognosis of this very common disorder?</strong></p><p>E Allers</p><p><strong>3. Can we prolong our patients' life expectancy? Providing a better quality of life for patients with severe mental illness</strong></p><p>O A Betencourt</p><p><strong>4. The scope of ECT practice in South Africa</strong></p><p>J Benson-Martin, P Milligan</p><p><strong>5. Biomarkers for schizophrenia: Can we evolve like cancer therapeutics?</strong></p><p>P Buckley<strong></strong></p><p><strong>6. Relapse in schizophrenis: Major challenges in prediction and prevention</strong></p><p>P Buckley</p><p><strong>7. Informed consent in biological treatments: The right to know the duty to inform</strong></p><p><strong></strong>I Chetty</p><p><strong>8. Effectiveness of a long-acting injectable antipsychotic plus an assertive monitoring programme in first-episode schizophrenia</strong></p><p><strong></strong>B Chiliza, L Asmal, O Esan, A Ojagbemi, O Gureje, R Emsley</p><p><strong>9. Name, shame, fame</strong></p><p>P Cilliers</p><p><strong>10. Can we manage the increasing incidence of violent raging children? We have to!</strong></p><p>H Clark</p><p><strong>11. Serotonin, depression and antidepressant action</strong></p><p>P Cowen</p><p><strong>12. Prevalence and correlates of comorbid psychiatris illness in patients with heroin use disorder admitted to Stikland Opioid Detoxification Unit</strong></p><p>L Dannatt, K J Cloete, M Kidd, L Weich</p><p><strong>13. Investigating the association between diabetes mellitus, depression and psychological distress in a cohort of South African teachers</strong></p><p>A K Domingo, S Seedat, T M Esterhuizen, C Laurence, J Volmink, L Asmal</p><p><strong>14. Neuropeptide S -emerging evidence for a role in anxiety</strong></p><p>K Domschke</p><p><strong>15. Pathogenetics of anxiety</strong></p><p>K Domschke</p><p><strong>16. The effects of HIV on the fronto-striatal system</strong></p><p>S du Plessis, M Vink, J Joska, E Koutsilieri, C Scheller, B Spottiswoode, D Stein, R Emsley</p><p><strong>17. Effects of acute antipsychotic treatment on brain morphology in schizophrenia</strong></p><p>R Emsley, L Asmal, B Chiliza, S du Plessis, J Carr, A Goosen, M Kidd, M Vink, R Kahn</p><p><strong>18. Development of a genetic database resource for monitoring of breast cancer patients at risk of physical and psychological complications</strong></p><p>K Grant, F J Cronje, K Botha, J P Apffelstaedt, M J Kotze</p><p><strong>19. Unipolar mania reconsidered: Evidence from a South African study</strong></p><p><strong></strong>C Grobler</p><p><strong>20. Antipsychotic-induced movement disorders: Occurence and management</strong></p><p>P Haddad</p><p><strong>21. The place of observational studies in assessing the effectiveness of long-acting injectable antipsychotics</strong></p><p>P Haddad</p><p><strong>22. Molecular mechanisms of d-cycloserine in fear extinction: Insights from RNS sequencing</strong></p><p>S Hemmings, S Malan-Muller, L Fairbairn, M Jalali, E J Oakeley, J Gamieldien, M Kidd, S Seedat</p><p><strong>23. Schizophrenia: The role of inflammation</strong></p><p>DC Henderson</p><p><strong>24. Addictions: Emergent trends and innovations</strong></p><p>V Hitzeroth</p><p><strong>25. The socio-cultural-religious context of biological psychiatric practice</strong></p><p>B Janse van Rensburg</p><p><strong>26. Biochemical markers for identifying risk factors for disability progression in multiple sclerosis</strong></p><p><strong></strong>S Janse van Rensburg, M J Kotze, F J Cronje, W Davis, K Moremi, M Jalali Sefid Dashti, J Gamieldien, D Geiger, M Rensburg, R van Toorn, M J de Klerk, G M Hon, T Matsha, S Hassan, R T Erasmus</p><p><strong>27. Alcohol-induced psychotic disorder: Brain perfusion and psychopathology - before and after antipsychotic treatment</strong></p><p>G Jordaan, J M Warwick, D G Nel, R Hewlett, R Emsley</p><p><strong>28.'Pump and dump': Harm reduction strategies for breastfeeding while using substances</strong></p><p>L Kramer</p><p><strong>29. Adolescent neuropsychiatry - an emerging field in South African adolescent psychiatric services</strong></p><p>A Lachman</p><p><strong>30. Recovery versus remission, or what it means to be healthy for a psychiatric patient?</strong></p><p>B Latecki</p><p><strong>31. Holistic methods utilised to normalise behaviours in youth diagnosed with neuro-biochemical disorders</strong></p><p>P Macqueen</p><p><strong>32. Candidate genes and novel polymorphisms for anxiety disorder in a South African cohort</strong></p><p>N McGregor, J Dimatelis, S M J Hemmings, C J Kinnear, D Stein, V Russel, C Lochner</p><p><strong>33. Higher visual functioning</strong></p><p>A Moodley</p><p><strong>34. The effects of prenatal methylmercury exposure on trace element and antioxidant levels in rat offspring following 6-hydroxydopamine-induced neuronal insult</strong></p><p>Z M Moosa, W M U Daniels, M V Mabandla</p><p><strong>35. Paediatric neuropsychiatric movement disorders</strong></p><p>L Mubaiwa</p><p><strong>36. The South African national female offenders study</strong></p><p>M Nagdee, L Artz, C de Clercq, P de Wet, H Erlacher, S Kaliski, C Kotze, L Kowalski, J Naidoo, S Naidoo, J Pretorius, M Roffey, F Sokudela, U Subramaney</p><p><strong>37. Neurobiological consequences of child abuse</strong></p><p>C Nemeroff</p><p><strong>38. What do Stellenbosch Unviversity medical students think about psychiatry - and why should we care?</strong></p><p>G Nortje, S Suliman, K Seed, G Lydall, S Seedat</p><p><strong>39. Neurological soft skins in Nigerian Africans with first episode schizophrenia: Factor structure and clinical correlates</strong></p><p><strong></strong>A Ojagbemi, O Esan, O Gureje, R Emsley</p><p><strong>40. Should psychiatric patients know their MTHFR status?</strong></p><p>E Peter</p><p><strong>41. Clinical and functional outcome of treatment refractory first-episode schizophrenia</strong></p><p>L Phahladira, R Emsley, L Asmal, B Chiliza</p><p><strong>42. Bioethics by case discussion</strong></p><p>W Pienaar</p><p><strong>43. Reviewing our social contract pertaining to psychiatric research in children, research in developing countries and distributive justice in pharmacy</strong></p><p>W Pienaar</p><p><strong>44. The performance of the MMSE in a heterogenous elderly South African population</strong></p><p>S Ramlall, J Chipps, A I Bhigjee, B J Pillay</p><p><strong>45. Biological basis addiction (alocohol and drug addiction)</strong></p><p>S Rataemane</p><p><strong>46. Volumetric brain changes in prenatal methamphetamine-exposed children compared with healthy unexposed controls</strong></p><p><strong></strong>A Roos, K Donald, G Jones, D J Stein</p><p><strong>47. Single voxel proton magnetic resonance spectroscopy of the amygdala in social anxiety disorder in the context of early developmental trauma</strong></p><p>D Rosenstein, A Hess, S Seedat, E Meintjies</p><p><strong>48. Discussion of HDAC inhibitors, with specific reference to supliride and its use during breastfeeding</strong></p><p>J Roux</p><p><strong>49. Prevalence and clinical correlates of police contact prior to a first diagnosis of schizophrenia</strong></p><p>C Schumann, L Asmal, K Cloete, B Chiliza, R Emsley</p><p><strong>50. Are dreams meaningless?</strong></p><p>M Solms</p><p><strong>51. The conscious id</strong></p><p>M Solms<strong></strong></p><p><strong>52. Depression and resilience in HIV-infected women with early life stress: Does trauma play a mediating role?</strong></p><p>G Spies, S Seedat</p><p><strong>53. State of affairs analysis for forensic psychiatry in SA</strong></p><p>U Subramaney</p><p><strong>54. Escitalopram in the prevention of post-traumatic stress disorder: A pilot randomised controlled trial</strong></p><p>S Suliman, S Seedat, J Pingo, T Sutherland, J Zohar, D J Stein</p><p><strong>55. Epigenetic consequences of adverse early social experiences in primates</strong></p><p>S Suomi</p><p><strong>56. Risk, resilience, and gene x environment interactions in primates</strong></p><p>S Suomi</p><p><strong>57. Biological aspects of anorexia nervosa</strong></p><p>C Szabo</p><p><strong>58. Agents used and profiles of non-fatal suicidal behaviour in East London</strong></p><p>H Uys</p><p><strong>59. The contributions of G-protein coupled receptor signalling to opioid dependence</strong></p><p>J van Tonder</p><p><strong>60. Emerging trend and innovation in PTSD and OCD</strong></p><p>J Zohar</p><p><strong>61. Making the SASOP treatment guidelines operational</strong></p><p>E Allers</p><p><strong>Poster Presentations</strong></p><p><strong>62. Neuropsychological deficits in social anxiety disorder in the context of early developmental trauma</strong></p><p><strong></strong>S Bakelaar, D Rosenstein, S Seedat</p><p><strong>63.Social anxiety disorder in patients with or without early childhood trauma: Relationship to behavioral inhibition and activation and quality of life</strong></p><p><strong></strong>S Bakelaar, C Bruijnen, A Sambeth, S Seedat</p><p><strong>64. Exploring altered affective processing in obssessive compulsive disorder symptom subtypes</strong></p><p>E Breet, J Ipser, D Stein, C Lochner<strong><br /></strong></p><p><strong>65. To investigate the bias toward recognising the facial expression of disgust in obsessive compulsive disorder as well as the effect of escitalopram</strong></p><p>E Breet, J Ipser, D Stein, C Lochner</p><p><strong>66. A fatal-case of nevirapine-induced Stevens-Johnson's syndrome in HIV mania</strong></p><p>A Bronkhorst, Z Zingela, W M Qwesha, B P Magigaba<strong></strong></p><p><strong>67. Association of the COMT G472A (met/met) genotype with lower disability in people diagnosed with multiple sclerosis</strong></p><p>W Davis, S J van Rensburg, L Fisher, F J Cronje, D Geiger, M J Kotze</p><p><strong>68. Homocycsteine levels are associated with the fat mass and obesity associated gene FTO(intron 1 T>A) polymorphism in MS patients</strong></p><p>W Davis, S J Van Rensburg, M J Kotze, L Fisher, M Jalali, F J Cronje, K Moremi, J Gamieldien, D Geiger, M Rensburg, R van Toorn, M J de Klerk, G M Hon, T Matsha, S Hassan, R T Erasmus</p><p><strong>69. Analysis of the COMT 472 G>A (rs4680) polymorphism in relation to environmental influences as contributing factors in patients with schizophrenia</strong></p><p>D de Klerk, S J van Rensburg, R A Emsley, D Geiger, M Rensburg, R T Erasmus, M J Kotze</p><p><strong>70. Dietary folate intake, homocysteine levels and MTHFR mutation detection in South African patients with depression: Test development for clinical application </strong></p><p>D Delport, N vand der Merwe, R Schoeman, M J Kotze</p><p><strong>71. The use ofexome sequencing for antipsychotic pharmacogenomic applications in South African schizophrenia patients</strong></p><p>B Drogmoller, D Niehaus, G Wright, B Chiliza, L Asmal, R Emsley, L Warnich</p><p><strong>72. The effects of HIV on the ventral-striatal reward system</strong></p><p>S du Plessis, M Vink, J Joska, E Koutsilieri, C Scheller, B Spottiswoode, D Stein, R Emsley</p><p><strong>73. Xenomelia relates to asymmetrical insular activity: A case study of fMRI</strong></p><p>S du Plessis, M Vink, L Asmal</p><p><strong>74. Maternal mental helath: A prospective naturalistic study of the outcome of pregancy in women with major psychiatric disorders in an African country</strong></p><p>E du Toit, L Koen, D Niehaus, B Vythilingum, E Jordaan, J Leppanen</p><p><strong>75. Prefrontal cortical thinning and subcortical volume decrease in HIV-positive children with encephalopathy</strong></p><p>J P Fouche, B Spottiswoode, K Donald, D Stein, J Hoare</p><p><strong>76. H-magnetic resonance spectroscopy metabolites in schizophrenia</strong></p><p>F Howells, J Hsieh, H Temmingh, D J Stein</p><p><strong>77. Hypothesis for the development of persistent methamphetamine-induced psychosis</strong></p><p><strong></strong> J Hsieh, D J Stein, F M Howells</p><p><strong>78. Culture, religion, spirituality and psychiatric practice: The SASOP Spirituality and Psychiatry Special Interest Group Action Plan for 2012-2014</strong></p><p>B Janse van Rensburg</p><p><strong>79. Cocaine reduces the efficiency of dopamine uptake in a rodent model of attention-deficit/hyperactivity disorder: An <em>in vivo</em> electrochemical study</strong></p><p><strong></strong>L Kellaway, J S Womersley, D J Stein, G A Gerhardt, V A Russell</p><p><strong>80. Kleine-Levin syndrome: Case in an adolescent psychiatric unit</strong></p><p>A Lachman</p><p><strong>81. Increased inflammatory stress specific clinical, lifestyle and therapeutic variables in patients receiving treatment for stress, anxiety or depressive symptoms</strong></p><p>H Luckhoff, M Kotze, S Janse van Rensburg, D Geiger</p><p><strong>82. Catatonia: An eight-case series report</strong></p><p>M Mabenge, Z Zingela, S van Wyk</p><p><strong>83. Relationship between anxiety sensitivity and childhood trauma in a random sample of adolescents from secondary schools in Cape Town</strong></p><p>L Martin, M Viljoen, S Seedat</p><p><strong>84. 'Making ethics real'. An overview of an ethics course presented by Fraser Health Ethics Services, BC, Canada</strong></p><p>JJ McCallaghan</p><p><strong>85. Clozapine discontinuation rates in a public healthcare setting</strong></p><p>M Moolman, W Esterhuysen, R Joubert, J C Lamprecht, M S Lubbe</p><p><strong>86. Retrospective review of clozapine monitoring in a publica sector psychiatric hospital and associated clinics</strong></p><p>M Moolman, W Esterhuysen, R Joubert, J C Lamprecht, M S Lubbe</p><p><strong>87. Association of an iron-related TMPRSS6 genetic variant c.2007 C>7 (rs855791) with functional iron deficiency and its effect on multiple sclerosis risk in the South African population</strong></p><p>K Moremi, S J van Rensburg, L R Fisher, W Davis, F J Cronje, M Jalali Sefid Dashti, J Gamieldien, D Geiger, M Rensburg, R van Toorn, M J de Klerk, G M Hon, T Matsha, S Hassan, R T Erasmus, M Kidd, M J Kotze</p><p><strong>88. Identifying molecular mechanisms of apormophine-induced addictive behaviours</strong></p><p>Z Ndlazi, W Daniels, M Mabandla</p><p><strong>89. Effects of lifestyle factors and biochemistry on the major neck blood vessels in patients with mutiple sclerosis</strong></p><p>M Nelson, S J van Rensburg, M J Kotze, F Isaacs, S Hassan</p><p><strong>90. Nicotine protects against dopamine neurodegenration and improves motor deficits in a Parkinsonian rat model</strong></p><p>N Ngema, P Ngema, M Mabandla, W Daniels</p><p><strong>91. Cognition: Probing anatomical substrates</strong></p><p>H Nowbath</p><p><strong>92. Chronic exposure to light reverses the effects of maternal separation on the rat prefrontal cortex</strong></p><p>V Russel, J Dimatelis</p><p><strong>93. Evaluating a new drug to combat Alzheimer's disease</strong></p><p>S Sibiya, W M U Daniels, M V Mabandla</p><p><strong>94. Structural brain changes in HIV-infected women with and without childhood trauma</strong></p><p>G Spies, F Ahmed, C Fennema-Notestine, S Archibald, S Seedat</p><p><strong>95. Nicotine-stimulated release of hippocampal norepinephrine is reduced in an animal model of attention-deficit/ hyperactivity disorder: the spontaneously hypertensive rat</strong></p><p>T Sterley</p><p><strong>96. Brain-derive neurotrophic factor (BDNF) protein levels in anxiety disorders: Systematic review and meta-regression analysis</strong></p><p>S Suliman, S M J Hemmings, S Seedat</p><p><strong>97. A 12-month retrospective audit of the demographic and clinical profile of mental healthcare users admitted to a district level hospital in the Western Cape, South Africa</strong></p><p>E Thomas, K J Cloete, M Kidd, H Lategan</p><p><strong>98. Magnesium recurarization: A comparison between reversal of neuromuscular block with sugammadex v. neostigmine/ glycopyrrolate in an <em>in vivo</em> rat model</strong></p><p><strong></strong>M van den Berg, M F M James, L A Kellaway</p><p><strong>99. Identification of breast cancer patients at increased risk of 'chemobrain': Case study and review of the literature</strong></p><p>N van der Merwe, R Pienaar, S J van Rensburg, J Bezuidenhout, M J Kotze</p><p><strong>100. The protective role of HAART and NAZA in HIV Tat protein-induced hippocampal cell death</strong></p><p>S Zulu, W M U Daniels, M V Mabandla</p>

<strong>Background:</strong>&nbsp;The term developmental delay denotes a significant delay in one or more developmental domains in humans. The importance of evaluation of a child with developmental delay lies in early diagnosis and treatment and also parental counseling regarding the outcome of their child and to identify any possible risk of recurrence in the siblings. This study is done to evaluate Magnetic Resonance Imaging (MRI) as an investigative modality for evaluation and to correlate the spectrum of findings in such patients with developmental delay. <strong>Methods:</strong>&nbsp;This is a prospective observational study done at the Department of Radiodiagnosis, Jorhat Medical College and Hospital from January 2022 to December 2022 with a sample size of 12 cases. All patients were evaluated clinically and underwent an MRI of the brain performed using a 1.5 Tesla MRI scanner. MRI scan was done and findings are recorded. <strong>Results:</strong>&nbsp;Among the cases, 3 have white matter disorders, 3 cases have Hypoxic Ischemic Encephalopathy (HIE), 2 cases have Cerebral atrophy with encephalomalacic changes, 1 case showing sub-ependymal heterotopia and 3 cases have normal findings. <strong>Conclusions:</strong>&nbsp;The spectrum of developmental delay is wide and MRI brain helps in proper diagnosis. This leads to appropriate treatment and parent counselling. Further, advanced imaging modalities like Functional MRI, MR Spectroscopy, Diffusion Tensor Imaging etc. helps in further evaluation of developmental delay. &nbsp;

ObjectiveVariants in several potassium channel genes, including KCNA1 and KCNA2, cause Developmental and Epileptic Encephalopathies (DEEs). We investigated whether variants in KCNA3, another mammalian homologue of the Drosophila shaker family and encoding for Kv1.3 subunits, can cause DEE.MethodsGenetic analysis of study individuals was performed by routine exome or genome sequencing, usually of parent‐offspring trios. Phenotyping was performed via a standard clinical questionnaire. Currents from wild‐type and/or mutant Kv1.3 subunits were investigated by whole‐cell patch‐clamp upon their heterologous expression.ResultsFourteen individuals, each carrying a de novo heterozygous missense variant in KCNA3, were identified. Most (12/14; 86%) had DEE with marked speech delay with or without motor delay, intellectual disability, epilepsy, and autism spectrum disorder. Functional analysis of Kv1.3 channels carrying each variant revealed heterogeneous functional changes, ranging from “pure” loss‐of‐function (LoF) effects due to faster inactivation kinetics, depolarized voltage‐dependence of activation, slower activation kinetics, increased current inactivation, reduced or absent currents with or without dominant‐negative effects, to “mixed” loss‐ and gain‐of‐function (GoF) effects. Compared to controls, Kv1.3 currents in lymphoblasts from one of the proband displayed functional changes similar to those observed upon heterologous expression of channels carrying the same variant. The antidepressant drug fluoxetine inhibited with similar potency the currents from wild‐type and one of the Kv1.3 GoF variant.InterpretationWe describe a novel association of de novo missense variants in KCNA3 with a human DEE, and provide evidence that fluoxetine might represent a potential targeted treatment for individuals carrying variants with significant GoF effects.This article is protected by copyright. All rights reserved.

SummaryBiallelic pathogenic variants in CAD, that encode the multienzymatic protein required for de‐novo pyrimidine biosynthesis, cause early infantile epileptic encephalopathy‐50. This rare disease, characterized by developmental delay, intractable seizures and anaemia, is amenable to treatment with uridine. We present a patient with macrocytic anaemia, elevated haemoglobin‐A2 levels, anisocytosis, poikilocytosis and target cells in the blood smear, and mild developmental delay. A next‐generation sequencing panel revealed biallelic variants in CAD. Functional studies did not support complete abrogation of protein function; however, the patient responded to uridine supplement. We conclude that biallelic hypomorphic CAD variants may cause a primarily haematological phenotype.

Magnetic resonance imaging (MRI) and Proton magnetic resonance spectroscopy (1HMRS) plays an important role in assessment and prognostication of the brain damage due to perinatal hypoxic-ischemic encephalopathy (HIE). Serial imaging is superior and is more useful especially in the prognostication. The aim of the present study was to assess the Temporal evolution of morphological brain changes on conventional MR imaging sequences and brain metabolites on MRS in deep gray matter as early as possible after birth, their status on follow up MRI scan in first 6 months of life. A prospective observational study was performed between October 2020 and September 2021. 31 full-term neonates with HIE, were included. Two sequential MR studies were performed; a conventional MR imaging, and proton MR spectroscopy for observation in the deep gray matter. Morphological brain changes were studied in the form of MRI scoring system. Followup with clinical examination for neurodevelopmental delay was done in our pediatric neurology clinic at 6 to 7 months of age. Mean MRI score in the first scan was found out to be 5.58 and in the second scan it was around 2.25. 30 subjects out of 31 showed lactate peak in the first scan and on followup imaging 8 out of 30 infants showed persistence of lactate peak (P value &lt; 0.0001), 27 (87.1 %) out of 31 subjects showed increase in NAA/Cr ratio on followup scan and 4 (12.9%) subjects showed decrease in NAA/Cr ratio. 5 out of 31 infants showed developmental delay, one infant expired and 25 infants (80 %) had no significant developmental delay. In conclusion there is significant correlation between persistence of lactate peak, decrease in NAA/Cr ratio and increased MRI score with neurodevelopmental delay.&#x0D; Keywords: Hypoxic-ischemic encephalopathy, Magentic resonance spectroscopy, Lactate peak, NAA/Cr ratio, neurodevelopmental delay, serial MRI.

Abstract FZR1, which encodes the Cdh1 subunit of the Anaphase Promoting Complex, plays an important role in neurodevelopment by regulating the cell cycle and by its multiple post-mitotic functions in neurons. In this study, evaluation of 250 unrelated patients with developmental and epileptic encephalopathies and a connection on GeneMatcher led to the identification of three de novo missense variants in FZR1. Whole-exome sequencing in 39 patient-parent trios and subsequent targeted sequencing in an additional cohort of 211 patients was performed to identify novel genes involved in developmental and epileptic encephalopathy. Functional studies in Drosophila were performed using three different mutant alleles of the Drosophila homolog of FZR1 fzr. All three individuals carrying de novo variants in FZR1 had childhood onset generalized epilepsy, intellectual disability, mild ataxia and normal head circumference. Two individuals were diagnosed with the developmental and epileptic encephalopathy subtype Myoclonic Atonic Epilepsy. We provide genetic-association testing using two independent statistical tests to support FZR1 association with developmental epileptic encephalopathies. Further, we provide functional evidence that the missense variants are loss-of-function alleles using Drosophila neurodevelopment assays. Using three fly mutant alleles of the Drosophila homolog fzr and overexpression studies, we show that patient variants can affect proper neurodevelopment. With the recent report of a patient with neonatal-onset with microcephaly who also carries a de novo FZR1 missense variant, our study consolidates the relationship between FZR1 and developmental epileptic encephalopathy, and expands the associated phenotype. We conclude that heterozygous loss-of-function of FZR1 leads to developmental epileptic encephalopathies associated with a spectrum of neonatal to childhood onset seizure types, developmental delay and mild ataxia. Microcephaly can be present but is not an essential feature of FZR1-encephalopathy. In summary, our approach of targeted sequencing using novel gene candidates and functional testing in Drosophila will help solve undiagnosed myoclonic atonic epilepsy or developmental epileptic encephalopathy cases.

BackgroundDevelopmental and epileptic encephalopathy (DEE) is a condition characterized by severe seizures and a range of developmental impairments. Pathogenic variants in KCNQ2, encoding for potassium channel subunit, cause KCNQ2-related DEE. This study aimed to examine the relationships between genotype and phenotype in KCNQ2-related DEE.MethodsIn total, 12 patients were enrolled in this study for genetic testing, clinical analysis, and developmental evaluation. Pathogenic variants of KCNQ2 were characterized through a whole-cell electrophysiological recording expressed in Chinese hamster ovary (CHO) cells. The expression levels of the KCNQ2 subunit and its localization at the plasma membrane were determined using Western blot analysis.ResultsSeizures were detected in all patients. All DEE patients showed evidence of developmental delay. In total, 11 de novo KCNQ2 variants were identified, including 10 missense variants from DEE patients and one truncating variant from a patient with self-limited neonatal epilepsy (SeLNE). All variants were found to be loss of function through analysis of M-currents using patch-clamp recordings. The functional impact of variants on M-current in heteromericKCNQ2/3 channels may be associated with the severity of developmental disorders in DEE. The variants with dominant-negative effects in heteromeric channels may be responsible for the profound developmental phenotype.ConclusionThe mechanism underlying KCNQ2-related DEE involves a reduction of the M-current through dominant-negative effects, and the severity of developmental disorders in DEE may be predicted by the impact of variants on the M-current of heteromericKCNQ2/3 channels.

The isoleucine–glutamine (IQ) motif and Sec7 domain-containing protein 2 (IQSEC2) gene, located at Xp11. 2, are associated with nervous system diseases, such as epilepsy, autism, and intellectual disabilities. Gender-related differences in the severity of phenotype severity have been described previously. Here, we report the details of seven male children with IQSEC2 mutations from different families. During this investigation, we explored the relationship between the genotype and phenotype of IQSEC2 mutations; to do so, we recruited seven children with pathogenic/likely pathogenic IQSEC2 mutations who were diagnosed with global developmental delay and/or epilepsy. Their clinical features were assessed, and Trio-based whole-exome sequencing (trio WES) was conducted in seven pedigrees. A variety of algorithms and computational tools were used to calculate the pathogenicity, protein stability, conservation, side chain properties, and protein-protein interactions of mutated proteins. The seven patients ranged in age from 18 months to 5 years. Among them, six children were found to have both developmental delay and epilepsy, and one child only exhibited developmental delay. Four novel mutations (c.316C &amp;gt; T, c.443_4 44dup, c.3235T &amp;gt; C, and c.1417G &amp;gt; T) were newly reported. Two patients did not have truncated aberrant proteins caused by missense mutations. Still, they did have severe phenotypes, such as early-onset epilepsy in infancy, because the mutations were located in domains like the pleckstrin homology and IQ calmodulin-binding motif domains. The bioinformatics analysis also proved that missense mutations may be located in the functional region, which affects protein stability and is harmful. In summary, severe phenotypes, such as early-onset epilepsy in infancy, occur in male patients with a missense mutation in specific domains (e.g., pleckstrin homology and IQ calmodulin-binding motif domains). Some female individuals with IQSEC2 mutations may be asymptomatic because of the skewed inactivation of the X chromosome.

Abstract GNAO1 encephalopathy is a neurodevelopmental disorder with a spectrum of symptoms that include dystonic movements, seizures and developmental delay. While numerous GNAO1 mutations are associated with this disorder, the functional consequences of pathological variants are not completely understood. Here, we deployed the invertebrate C. elegans as a whole-animal behavioral model to study the functional effects of GNAO1 disorder-associated mutations. We tested several pathological GNAO1 mutations for effects on locomotor behaviors using a combination of CRISPR/Cas9 gene editing and transgenic overexpression in vivo. We report that all three mutations tested (G42R, G203R and R209C) result in strong loss of function defects when evaluated as homozygous CRISPR alleles. In addition, mutations produced dominant negative effects assessed using both heterozygous CRISPR alleles and transgenic overexpression. Experiments in mice confirmed dominant negative effects of GNAO1 G42R, which impaired numerous motor behaviors. Thus, GNAO1 pathological mutations result in conserved functional outcomes across animal models. Our study further establishes the molecular genetic basis of GNAO1 encephalopathy, and develops a CRISPR-based pipeline for functionally evaluating mutations associated with neurodevelopmental disorders.

Abstract Here, we report on six unrelated individuals, all presenting with early-onset global developmental delay, associated with impaired motor, speech and cognitive development, partly with developmental epileptic encephalopathy and physical dysmorphisms. All individuals carry heterozygous missense variants of KCND2, which encodes the voltage-gated potassium (Kv) channel α-subunit Kv4.2. The amino acid substitutions associated with the variants, p.(Glu323Lys) (E323K), p.(Pro403Ala) (P403A), p.(Val404Leu) (V404L) and p.(Val404Met) (V404M), affect sites known to be critical for channel gating. To unravel their likely pathogenicity, recombinant mutant channels were studied in the absence and presence of auxiliary β-subunits under two-electrode voltage clamp in Xenopus oocytes. All channel mutants exhibited slowed and incomplete macroscopic inactivation, and the P403A variant in addition slowed activation. Co-expression of KChIP2 or DPP6 augmented the functional expression of both wild-type and mutant channels; however, the auxiliary β-subunit-mediated gating modifications differed from wild type and among mutants. To simulate the putative setting in the affected individuals, heteromeric Kv4.2 channels (wild type + mutant) were studied as ternary complexes (containing both KChIP2 and DPP6). In the heteromeric ternary configuration, the E323K variant exhibited only marginal functional alterations compared to homomeric wild-type ternary, compatible with mild loss-of-function. By contrast, the P403A, V404L and V404M variants displayed strong gating impairment in the heteromeric ternary configuration, compatible with loss-of-function or gain-of-function. Our results support the etiological involvement of Kv4.2 channel gating impairment in early-onset monogenic global developmental delay. In addition, they suggest that gain-of-function mechanisms associated with a substitution of V404 increase epileptic seizure susceptibility.