The benefits and limitations of expanded Y-chromosome short tandem repeat (Y-STR) loci

Recent advances in commercially available Y-chromosome short tandem repeat (Y-STR) profiling kits include the development of expanded locus sets and the inclusion of rapidly mutating (RM) Y-STR loci. Thermo Fisher Scientific recently released its Yfiler^® Plus (YF+) kit to the forensic market. Yfiler^® Plus has 27 loci, including 7 RM Y-STRs and full locus overlap with its predecessor AmpFlSTR® Yfiler™ (Yfiler). Forensic Science SA has been using Yfiler in routine forensic casework since 2007 but recently evaluated YF+ due to its apparent increased sensitivity and discrimination power. As with any transition to a new multiplex, there are benefits and limitations which need to be considered by each laboratory before implementation proceeds. Whilst there are a number of cost, profile interpretational and laboratory issues that need to be overcome, the benefits that YF+ provides over Yfiler will result in FSSA implementing this expanded multiplex for forensic casework.