Y-STR loci diversity in native Alaskan populations.

Y chromosome short tandem repeat (Y-STR) loci are important genetic markers for forensic biological evidence analyses. However, paternal inheritance, reduced effective population size, and lack of independence between loci can reduce Y-STR diversity and may yield greater population substructure effects on a locus-by-locus basis compared with the autosomal STR loci. Population studies are necessary to assess the genetic variation of forensically relevant markers so that proper inferences can be made about the rarity of DNA profiles. This study examined 16 Y-STRs in three sampled populations of Native Americans from Alaska: Inupiat, Yupik, and Athabaskan. Population genetic and statistical issues addressed were: (1) the degree of diversity at locus and haplotype levels, (2) determination of the loci that contribute more so to haplotype diversity, and (3) the effects of population substructure on forensic statistical calculations of the rarity of a Y-STR profile. All three population samples were highly polymorphic at the haplotype level for the 16 Y-STR markers; however, the Native Americans demonstrated reduced genetic diversity compared with major US populations. The degree of substructure indicated that the three populations were related and admixed in terms of paternal lineage. The examination of more polymorphic loci may be needed to increase the power of discrimination of Y-STR systems in these populations.

Population studies on three Native Alaska population groups using STR loci.

Allele distributions for 13 short tandem repeat (STR) loci D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, TH01, TPOX, CSF1PO and D16S539 were determined for three Native Alaskan population groups-Athabaskans, Inupiats, and Yupiks. Although genetic diversity is lower in the Native Alaskan populations compared with Caucasians and Africans, almost all loci are highly polymorphic in all three Native Alaskan groups. There was little evidence for departures from Hardy-Weinberg expectations (HWE) in any of the populations. Only two examples of detectable departures from HWE out of 39 locus-population tests performed were observed based on the exact test (Yupik, D8S1179, P=0.030; Yupik, D5S818, P=0.016). The F(ST) estimate overall 13 STR loci is 0.0309 for the Native Alaskan populations. Based on a genetic distance measure, Athabaskans are more closely related to Apaches and Navajos (all of the same linguistic group) than the other Native Alaskan groups. The F(ST) estimate for Athabaskans, Apaches and Navajos is 0.0180 and for Inupiats and Yupiks is 0.0167. The allele frequency data can be used for estimating DNA profile frequencies for Native Americans residing in Alaska.

Prototype PowerPlex® Y23 System: A concordance study.

The Prototype PowerPlex(®) Y23 System (Promega Corporation, Madison, WI) is a polymerase chain reaction-based amplification kit that targets the 23 Y STR loci DYS19, DYS385a/b, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS481, DYS533, DYS549, DYS570, DYS576, DYS635, DYS643, and Y-GATA-H4. A total of 951 samples from six populations were typed to evaluate the kit and examine concordance for 17 of the loci that are in common with those that can be typed using the AmpFlSTR(®) Yfiler™ kit (Life Technologies, Carlsbad, CA). A total of 16,167 loci were analyzed for each multiplex, and overall concordance was observed. Because of different kit designs, and although concordant for the genetic type, discordant calls can occur due to a deletion at the DYS448 locus. Users should take into consideration such nomenclature anomalies when comparing Y STR profiles. This new kit allows a large battery of Y STR loci to be analyzed using the same basic technologies already employed in forensic laboratories.