Forensic assessment of 16 single nucleotide polymorphisms analyzed by hybridization probe assay

Of a number of DNA marker typing techniques for personal identification in the field of forensic medicine, polymorphic short tandem repeat (STR) typing is currently the most frequently used technique. However, the multiplex STR method is time consuming. In contrast, single nucleotide polymorphism (SNP) detection methods are relatively rapid and amenable to high throughput. The discrimination power of each SNP is inferior to that of an STR, but a combination of many SNPs could realize a high discriminating power. In this regard, 16 highly informative SNP markers were selected in the introns of genes whose alleles had a proportion of 0.4-0.6 in the Japanese SNP database. The 16 SNPs were sequentially detected within 40 min using the hybridization probe assay on the Light-Cycler system. The allele and genotype frequencies of these SNPs were determined in a group comprising 64 unrelated Japanese subjects. Based on the frequency data of this group, the combined matching probability, defined as the estimated probability that two unrelated individuals selected at random would possess identical multilocus genotypes, was calculated with the 16 SNPs in the Japanese population and was found to be 2.025 × 10^-7. This system is an effective tool in the forensic medicine to obtain information on personal identification.