Development on practical examination methods using DNA polymorphisms in the field of Forensic Dentistry

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The purpose of this study is to establish practicable and reliable methods to detect DNA polyomorphisms using highly degraded DNA sources in Forensic Dentistry. In the first year, we examined if reduction of the PC size on STs gave reproducible results and also if it improved amplification efficiency from degraded DNAs. We compared reliability of amplification of the small-sized ST loci, such as D12SG6, VWA and CD4 and examined influences on typing when the primers producing different-sized PCB products from the same polymorphic region were constructed and applied to the PC. The results indicated that reduction of the PC size increased amplification efficiency from degraded DNAs, but did not coordinate reliability of typing. We investigated sequence polymorphism of mitochondrial DNA control regions from 201 Japanese individuals and classified 165 haplotypes into 32 clusters based on the results of Neighbour Joioning analysis. Each clusters shared specific polymorphic sites, and these characteristics suggested possible application of mtDNA polymorphisms to ethnic group estimation from forensic biological samples. We also investigated 10 Y chromosome ST polymorphisms in the Japanese population and also shoed structural variation in the DYS390 locus, resulting in the identification of highly informative discriminatory power of Y-ST polymorphisms. Beauses ST polymorphisms sometimes gave erroneous results in PC of degraded DNA, we extended our studies on Y-SNPs by designing primers to amplify small PC products, which made it possible to obtain amplification products from highly degraded DNAs. Autosomal ST polymerphisms and SNPs were also examined to compare reliability of typing from degraded DNA samples. Haplotype analysis on Y-SNPs indicated the presence of several lineages in male individuals in the Japanese population. We also showed procedure and resin used by the patients.