Screening of highly discriminative microhaplotype markers for individual identification and mixture deconvolution in East Asian populations

Abstract

Microhaplotypes are forensic genetic markers that combine single nucleotide polymorphisms in close proximity to one another. Highly discriminative microhaplotype markers could be superior to short tandem repeats (STRs) in DNA mixture deconvolution investigations because they are not interfered by stutters. In this study, the effective number of alleles (Ae) and discrimination power values of microhaplotypes and STRs were compared. It was found that current microhaplotypes are not as discriminative as commonly used forensic STRs. Effective screening of highly discriminative microhaplotype markers were consequently conducted for East Asian populations. To satisfy different forensic application needs, four sets of microhaplotypes with Ae values ≥ 4 were screened for under different conditions that included marker length and physical distances between markers. While the four sets contained 703, 301, 337, and 190 microhaplotypes, their average Ae values reached 5.38, 6.30, 7.39, and 5.61, respectively. The microhaplotype group containing 301 markers (maximum length of 200 bp and separated by ≥ 5 million bases) was further investigated. The results showed that none of the 301 loci were exactly the same as those previously reported, while seven loci partially overlapped with known markers. While Ae values of 45 loci were ≥ 8, the Ae value of the mh17WL-008 locus reached a maximum of 93.57. Further analysis showed that the newly identified microhaplotype markers were also highly polymorphic in African, American, European, and South Asian populations.