A multiplex PCR system for 13 RM Y-STRs with separate amplification of two different repeat motif structures in DYF403S1a.

In forensic science and human genetics, Y-chromosomal short tandem repeats (Y-STRs) have been used as very useful markers. Recently, more Y-STR markers have been analyzed to enhance the resolution power in haplotype analysis, and 13 rapidly mutating (RM) Y-STRs have been suggested as revolutionary tools that can widen Y-chromosomal application from paternal lineage differentiation to male individualization. We have constructed two multiplex PCR sets for the amplification of 13 RM Y-STRs, which yield small-sized amplicons (<400bp) and a more balanced PCR efficiency with minimum PCR cycling. In particular, with the developed multiplex PCR system, we could separate three copies of DYF403S1a into two copies of DYF403S1a and one of DYF403S1b1. This is because DYF403S1b1 possesses distinguishable sequences from DYF403S1a at both the front and rear flanking regions of the repeat motif; therefore, the locus could be separately amplified using sequence-specific primers. In addition, the other copy, defined as DYF403S1b by Ballantyne et al., was renamed DYF403S1b2 because of its similar flanking region sequence to DYF403S1b1. By redefining DYF403S1 with the developed multiplex system, all genotypes of four copies could be successfully typed and more diverse haplotypes were obtained. We analyzed haplotype distributions in 705 Korean males based on four different Y-STR subsets: Yfiler, PowerPlex Y23, Yfiler Plus, and RM Y-STRs. All haplotypes obtained from RM Y-STRs were the most diverse and showed strong discriminatory power in Korean population.