Subtyping of the HLA-DQA1 Locus and Independence Testing with PM and STR/VNTR Loci

Abstract

Allele and genotype frequencies for six loci (HLA-DQA1 and PM loci) were determined in African Americans, United States Caucasians, and Southwestern Hispanics. The data include allele frequencies of the HLA-DQA1 4 subtypes. The HLA-DQA1 4 allele subtyping affords greater power of discrimination in African Americans and Southwestern Hispanics than in Caucasians, due to the relatively lower 4.2/4.3 allele frequency in Caucasians. Based on the exact test, all loci, except the GYPA locus in the African American sample (p = 0.011), meet Hardy-Weinberg expectations. There were two examples of significant departures from expectations of independence between alleles of the HLA-DQA1 and PM loci (HBGG/Gc in African Americans, p = 0.30; LDLR/DQA1 in Caucasians, p = 0.023). The HLA-DQA1 and PM loci also were tested for associations with three STR loci and the DIS80 locus. There were four examples of significant departures from expectations of independence (TPOX/D7S8 and THO1/HBGG in African Americans, p = 0.035 and 0.028, respectively; THO1/LDLR in Caucasians, p = 0.028; and GYPA/D1S80 in Hispanics, p = 0.046). The HLA-DQA1 and PM allele frequency data were compared with previously reported data on other sample populations of the same population categories from our laboratory; the allele frequencies at all loci, except the D7S8 locus in Hispanics (p = 0.028), were statistically similar. The frequency data can be used in forensic analyses and paternity tests to estimate the frequency of a multiple locus DNA profile in various general United States populations.