Developmental validation of a novel 8‐dye fluorescent typing system with 59 Y‐STRs and 3 Y‐indels for forensic applications

Abstract

AbstractAn 8‐dye fluorescence‐labeling forensic Y‐chromosomal short tandem repeats (Y‐STRs) kit, the 62‐plex Y‐STR multiplex amplification system, was developed and optimized. The system was validated by testing PCR conditions, stutter ratios (SR) and peak height ratios, sensitivity, mixture samples, precision and accuracy, species‐specificity, and inhibition studies according to the Scientific Working Group on DNA Analysis Methods guidelines. PCR‐based studies showed that the recommended PCR conditions were optimized for this kit. In the sensitivity study, a full profile was obtained from template DNA with a quantity of u125 pg. Consistent profiles were obtained from three different laboratories. The SRs in all loci were less than 15%, and nice balance and suitable average peak height were shown. No peaks were detected in the profiles of common animal species and microorganisms. In the male–male mixture studies, all loci were observed at a ratio of 1:8, and in the male–female mixture study, all alleles could be profiled at a ratio of 1:500 if the male DNA inputs were ≥0.5 ng/µL. An inhibitor study demonstrated that the kit had varying degrees of resistance to the presence of common inhibitors. Population study demonstrated the 62‐plex Y‐STR Kit improved the power of discrimination in unrelated Chinese Han males (n = 192). When haplotype diversity was 1, the probability of discrimination power of the 62‐plex Y‐STR Kit was 0.9948, which is suitable for forensic investigations. The results show that the developed 8‐dye fluorescence labeling 62 loci system is sensitive, robust, convenient, and highly informative for forensic applications.