title: Additional Y-STRs in Forensics: Why, Which, and When.
abstract: Male-specific DNA profiling using nonrecombining Y-chromosomal genetic markers is becoming ubiquitous in forensic genetics, with many laboratories and jurisdictions taking advantage of the benefits that Y-chromosome short tandem repeat (Y-STR) profiling can bring. The current suite of 9-17 core Y-STRs, available as commercial kits, perform adequately for identifying male lineages in many populations, a feature highly suitable for excluding a male suspect from involvement in crimes such as sexual assaults where autosomal STR profiling is often troubled. However, there is a growing need to achieve higher resolution in paternal-lineage differentiation as adventitious matches between unrelated males are becoming increasingly common with the increasing size of Y-STR haplotype-frequency databases. Furthermore, with the currently used Y-STRs, male relatives (both close and distant) usually cannot be separated, marking a strong limitation in forensic applications as conclusions cannot be drawn on the individual level as desired. Performing Y-chromosome analysis in familial testing, which outperforms autosomal STR profiling in certain deficiency cases, with the current Y-STR sets can be troubled by mutations that complicate relationship-probability estimations. To overcome these limitations, considerable research has been performed over recent years to identify and characterize additional Y-STRs. This review summarizes the forensic performance of current sets of Y-STRs, points out their limitations in the three main areas of forensic Y-STR applications (male-lineage differentiation, male-relative differentiation, and paternity/familial testing), and discusses why and which additional Y-STRs are suitable to improve forensic Y-chromosome analysis in the future.
authors.affiliation: Forensic Services Department, Victoria Police, Macleod, Victoria, Australia.
authors.forename: K N
authors.initials: KN
authors.lastname: Ballantyne
authors.affiliation: Department of Forensic Molecular Biology, Erasmus MC University Medical Center Rotterdam, Rotterdam, South Holland, The Netherlands. m.kayser@erasmusmc.nl.
authors.forename: M
authors.initials: M
authors.lastname: Kayser
keywords: Deficiency cases; RM Y-STR; SM Y-STRs; Y chromosome; Y-STR; Yfiler; forensic; microsatellites; mutation rate; paternal lineage; paternity; sexual assault