Evaluation of the Microhaplotypes panel for DNA mixture analyses. (July 2018)

• Record Type: Journal Article
• Authors: Chen, Peng; Yin, Caiyong; Li, Zheng; Pu, Yan; Yu, Youjia; Zhao, Peng; Chen, Dexin; Liang, Weibo; Zhang, Lin; Chen, Feng
• Is Part Of: Forensic science international. Volume 35(2018)
• Page Start: 149
• Page End: 155
• Publication Date: 2018-07
• Subjects: Microhaplotype -- Mixture -- Effective number of alleles, Ae -- Likelihood ratio; Forensic genetics -- Periodicals; Génétique légale -- Périodiques; Forensic genetics; Electronic journals; Periodicals; 614.1
• DOI: 10.1016/j.fsigen.2018.05.003
• Languages: English
• ISSNs: 1872-4973

Abstract

Highlights: The first study to design a robust microhaplotype-based panel for DNA mixture analysis. We screened 26 microhaplotypes, each generating a relatively high effective number of alleles and possessing low sequence lengths. 14 of the 26 microhaps have been successfully multiplexed together, which were further tested by using massively parallel sequencing. 60 unrelated Chinese Han individuals and 2 artificially prepared samples mixed by two unrelated contributors were sequenced. Abstract: The identification of a suspect in a DNA mixture typed with the standard short tandem repeat polymorphism (STR) kits has faced challenges. Several improved methods or technologies have been introduced to address this issue. However, some complex situations in the process remain elusive. In the present study, we presented a panel of 26 tiny microhaplotypes, each generating a relatively high (>3.0) effective number of alleles (Ae ) and possessing low (<50 bp) sequence lengths. The average Ae and heterozygosity values among the 9 populations of 26 microhaps were in ranges from 2.60 to 4.54 and 0.59 to 0.96, respectively. Power of discrimination and power of exclusion values were ranged from 0.49 to 0.87 and 0.29 to 0.94, respectively. Significant positive correlations have been found between Ae values and heterozygosity (r = 0.43, p = 0.02) or power of discrimination values (r = 0.55, p = 0.003), respectively. The cumulative probability of detecting a mixture of two unrelated individuals could reach 0.9999998 when using a panel of 26 microhaps with Ae = 3. We further tested the panel by using massively parallel sequencing, and 14 out of 26 microhaps were successfully genotyped in a single multiplex system. 60 unrelated Chinese Han individuals and 2 artificially prepared samples mixed by two unrelated contributors (in duplicate, ie. 4 mixtures) were sequenced. Approximately 32.14% of the 14 loci presented three or four alleles in the two mixtures. The likelihood ratio values to cognizance the mixtures' contributor were in a range from 1.95 × 10 6 to 1.10 × 10 7 . The results demonstrated that the present panel could offer a valuable complementary tool in forensic applications.