Assessment of a subset of Slowly Mutating Y-STRs for forensic and evolutionary studies.

Y-specific short tandem repeat (Y-STR) loci display different mutation rates and consequently are suitable for forensic, genealogical, and evolutionary studies that require different levels of timelines and resolution. Recent efforts have focused on implementing Rapidly Mutating (RM) Y-STRs to assess male specific profiles. However, due to their high mutation rate their use in kinship testing or in phylogenetic studies may be less reliable. In the present study, a novel Slowly Mutating Y-STR (SM) panel, including DYS388, DYS426, DYS461 (Y-GATA-A7.2), DYS485, DYS525, and DYS561, has been developed and evaluated in a sample set of 628 unrelated males from different worldwide populations. This panel is reproducible, sensitive, and robust for forensic applications and may be useful in conjunction with the common multiplexes, particularly in exclusion of kinship cases where minimal discrimination is reported employing the rapidly mutating Y-STR systems. Furthermore, SM Y-STR data may be of value in evolutionary studies to optimize the resolution of phylogenetic relationships generated with current Y-STR panel sets. In this study, we provide an extensive Y-STR allele and haplotype reference dataset for future applications.

Analysis of the R1b-DF27 haplogroup shows that a large fraction of Iberian Y-chromosome lineages originated recently in situ.

Haplogroup R1b-M269 comprises most Western European Y chromosomes; of its main branches, R1b-DF27 is by far the least known, and it appears to be highly prevalent only in Iberia. We have genotyped 1072 R1b-DF27 chromosomes for six additional SNPs and 17 Y-STRs in population samples from Spain, Portugal and France in order to further characterize this lineage and, in particular, to ascertain the time and place where it originated, as well as its subsequent dynamics. We found that R1b-DF27 is present in frequencies ~40% in Iberian populations and up to 70% in Basques, but it drops quickly to 6-20% in France. Overall, the age of R1b-DF27 is estimated at ~4,200 years ago, at the transition between the Neolithic and the Bronze Age, when the Y chromosome landscape of W Europe was thoroughly remodeled. In spite of its high frequency in Basques, Y-STR internal diversity of R1b-DF27 is lower there, and results in more recent age estimates; NE Iberia is the most likely place of origin of DF27. Subhaplogroup frequencies within R1b-DF27 are geographically structured, and show domains that are reminiscent of the pre-Roman Celtic/Iberian division, or of the medieval Christian kingdoms.

17 to 23: A novel complementary mini Y-STR panel to extend the Y-STR databases from 17 to 23 markers for forensic purposes.

A Y-STR multiplex system has been developed with the purpose of complementing the widely used 17 Y-STR haplotyping (AmpFlSTR Y Filer® PCR Amplification kit) routinely employed in forensic and population genetic studies. This new multiplex system includes six additional STR loci (DYS576, DYS481, DYS549, DYS533, DYS570, and DYS643) to reach the 23 Y-STR of the PowerPlex® Y23 System. In addition, this kit includes the DYS456 and DYS385 loci for traceability purposes. Male samples from 625 individuals from ten worldwide populations were genotyped, including three sample sets from populations previously published with the 17 Y-STR system to expand their current data. Validation studies demonstrated good performance of the panel set in terms of concordance, sensitivity, and stability in the presence of inhibitors and artificially degraded DNA. The results obtained for haplotype diversity and discrimination capacity with this multiplex system were considerably high, providing further evidences of the suitability of this novel Y-STR system for forensic purposes. Thus, the use of this multiplex for samples previously genotyped with 17 Y-STRs will be an efficient and low-cost alternative to complete the set of 23 Y-STRs and improve allele databases for population and forensic purposes.

Forensic Spanish allele and haplotype database for a 17 X-STR panel.

The currently developed 17 X-STR panel (DXS8378, DXS9898, DXS7133, GATA31E08, GATA172D05, DXS6801, DXS7423, DXS6809, DXS6799, DXS7132, DXS9902, DXS6800, DXS6789, DXS10075, DXS10079, DXS6807, and DXS6803) offers a highly discriminative tool for forensic identification and kinship testing. With the aim of providing a global Spanish population X-STR database, we present haplotype and allele frequencies and parameters of forensic interest for the 17 X-STR panel obtained from 593 unrelated individuals from Alicante, Aragon, the Basque Country, Andalusia, Galicia, Madrid, and Barcelona that represent the most populated regions of the Spanish Peninsular territory. The seven populations were compared to test possible population genetic substructures. The lack of significant differences among the studied Spanish populations supports the use of the allele and haplotype frequency database presented herein as a global Spanish population sample useful for statistical evaluation in forensic casework. After conducting the LD plots derived from HapMap and pairwise linkage disequilibrium tests, DXS7132, DXS10075, and DXS10079 markers were included in a cluster and haplotype frequencies were calculated. The improvement in the forensic parameters for the Spanish population using 17 X-STRs in comparison to the previous 10 X-STR allele frequencies database is also shown.