Forensic molecular biological applications using single nucleotide polymorphisms (SNPs) regions

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In this study, we tried to establish the appropriate method to detect the genotypes of single nucleotide polymorphisms (SNPs) which are useful for forensic practice such as personal identification and paternity testing. At first, we tested several methods to search which is the best. We found that the allele specific PCR method is convenient for locus selection, and the SnapShot method is suitable for multiplex system. Then, we selected highly polymorphic 51 SNP loci in an Asian population being outside the region of the gene from those listed in the SNP Consortium. Among them, 39 loci were found to be in the Hardy-Weinberg equilibrium by x^2 method with 32 unrelated healthy Japanese. These 39 loci are highly polymorphic in Japanese ; 22 loci show the lower frequencies over than 0.4, and 14 show them over than 0.3. We are now establishing a new multiplex SNP typing system with the 12 out of these 14 loci, which distribute on different chromosome using the same techniques by which we have succeeded in the newly devised STR multiplex system. We also tried to establish a highly sensitive method for the minute and old specimens where DNA is highly degraded. We often get negative results in STR typing with such specimens because of the insufficient amplification. The PCR products of most STR loci are 150-300 bases, while those of SNP loci can be shortened to less than 100 bases. Therefore, SNP loci have a great advantage of the efficient amplification of degraded DNA. We could almost finish the development of the highly sensitive method for several SNP loci.