Characterization Of Ten Novel Y-STR Loci And Their Multiplex PCR Assay

Objective This study was carried out in order to explore new Y-STR markers and their multiplex PCR assay to improve the discrimination power of the Y chromosome for forensic applications. Method Firstly we sequenced the different alleles of ten novel Y-STR loci and constructed the allelic ladders. A total of 103 unrelated Chinese Han male samples was tested with the Y-STRs separately by PAGE with silver staining system. Secondly, we selected four Y-STR loci from them, which were DYS510, DYS520, DYS542 and DYS561, and constructed in an analysis system with multiplex PCR design strategy. The multiplex PCR products were detected on ABI PRISM^? 310 Genetic Analyzer using two labeling colors. Lastly, a series of validation experiments were carried out according to the suggestions by the Technical Working Group DNA Analysis Methods (TWGDAM). Result The ten loci we studied here were male-specific STRs on the Y chromosome, The number of alleles observed at these ten Y-STR loci ranged from 3 to 8, yielding 102 haplotypes in 103 unrelated males samples. The allele diversity values for each locus ranged from0.2099 (DYS544) to 0.7523 (DYS552). The haplotype diversity using all these loci was 0.9998. A tetra-multiplex PCR system (WCUMS-TETRA-Y, 4-Y) was established. The stability, robustness and sensitivity of the WCUMS-TETRA-Y were proved by validation experiments. For the male/male mixtures amplified with the 4-Y system, the minor component in the mixture could be identified up to a ratio of 1:50, while the analysis of the male/female mixtures revealed no interference of any female component, and could be identified up to a ratio of 1:2000. Conclusion Our study revealed that the ten Y-STR loci we studied were suitable candidate Y specific markers for forensic application in our population. They could provide additional discrimination for the forensic Y-STR typing. The tetra-multiplex system established was proved to be robust and reliable with both simulated and real casework samples. It can be applied for the forensic DNA typing.