EVALUATION OF TETRANUCLEOTIDE REPEAT LOCUS D7S809 (WG1G9) IN THE JAPANESE POPULATION

The tetrameric short tandem repeat (STR) locus (D7S809) has been evalu ated in the Japanese population. In order to detect the alleles, PCR w as carried out using primers, one of which was end labelled with P-32 and PCR products were separated by electrophoresis on a denaturing pol yacrylamide gel. Using this method, accurate genotypes could be determ ined from as little as 0.5 ng of genomic DNA, Thirteen different allel es were identified on 256 chromosomes tested. All alleles differed in size by one (4 bp) repeat unit, and no 'interalleles' were found. The estimated heterozygosity and the polymorphism information content (PIG ) were 0.86 and 0.83, respectively. We observed 42 of the 91 possible different genotypes. The power of discrimination (PD) was 0.96, and no significant deviations from the Hardy-Weinberg equilibrium were found . We retyped all apparently homozygous samples using an alternative pa ir of flanking primers in order to confirm homozygosity. We also demon strated a typing result involving sexual assault. D7S809 appears to be a very useful STR locus for forensic practice in Japanese.