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

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The purpose of this study is developing and improving practicable and reliable methods to detect DNA polymorphisms using highly degraded DNA sources in forensic casework. In the first year, we established the most detailed mtDNA phylogeny in the Japanese population and identified 33 haplogroups including 3 new lineages in 211 unrelated individuals. In the following years, we further investigated 79 coding region polymorphisms of mtDNA and classified 211 individuals into 197 types composed of 106 haplogroup lineages based on the information of almost whole mtDNA genome. We further increased 80 Japanese database and also found 9 new haplogroup lineages in 30 Malay individuals. Y chromosomal polymorphisms were investigated in 263 individuals in the Japanese population. We established the most detailed Y chromosomal phylogeny in the Japanese population using 40 kinds of biallelic markers and also examined 16 kinds of Y-STRs. These studied made it possible to estimate binary haplogroups using STR haplotypes. We also found that the hypervariable polymorphic locus 47z is very informative to estimate Y chromosomal binary haplogroups. These data showed that the information of mtDNA and Y chromosomal polymorphisms was useful not only for personal identification but also for geographic estimation in forensic casework. We investigated the influence of template DNA degradation on the genotyping of DNA polymorphisms and showed that the examination of SNPs is more reliable than that of STR polymorphisms. We further investigated polymorphisms on salivary protein gene family and conducted basic research related to clinical dentistry using recombinant polymorphic proteins. As mentioned above, we showed in this study that SNPs is more reliable for analysis on highly degraded DNAs. Thus we increased information of SNPs mainly on mtDNA and Y chromosomal DNA polymorphisms. We believe that we have developed highly useful methods of DNA analysis for practical Forensic Dentistry.