Academic literature on the topic 'Amplification large bande'

Positive identification is the ultimate objective of forensic analysis of blood and other tissue specimens. Nucleotide probes can be very effective tools for detecting genetic markers in this identification process. The genetic markers should be highly polymorphic; allelic variants should be easily and readily detectable; if amplification is required, the alleles should be efficiently amplified using PCR technology; and a statistically sound estimate of the population allele and genotype frequencies should be available. Probes are single-stranded fragments of DNA or RNA containing the complementary code for a specific sequence of genome bases. Probes available for DNA profile analysis will, no doubt, eventually number in the hundreds. Currently, the most valuable detect tandem repetitive sequence fragments either at a specific locus under high-stringency analysis conditions or at numerous loci under low-stringency conditions. Each locus consists of many possible alleles with frequencies that vary depending on the specific population. Other factors also enter into the selection of probes, including ease of amplification, stability, cross-reactivity, and general availability. Rate of allele mutation is also a prime consideration in probe selection. Mutation can be considered at two levels: as the basis for the large number of tandem repeat (VNTR) alleles formed during evolution and as a possible reason for spurious unassignable bands in typing analysis. Although highly unlikely, somatic mutations may be of concern in forensic testing if DNA from different tissues, such as blood and hair roots, are being matched. Germ line (gamete) mutations must be considered when parentage analyses are undertaken. These situations could give rise to false negative results and, therefore, false exclusions. Different considerations also apply for single versus multilocus probes. If a band that is not seen in the putative father is detected in an offspring, the man could incorrectly be excluded if the single-locus probe approach is used. This situation would necessitate testing with more than the usual four or five probes.