Relative HLA-DRB1*13 allele frequencies and DRB3 associations of unrelatedindividuals from five US populations

The frequencies of 30 HLA-DRB1*13 alleles and 15 DRB3 alleles were determin ed for the 5 major U.S. ethnic populations: Caucasians, African Americans, Asian/Pacific Islanders, Hispanics, and Native Americans. A random sampling (163) of DRB1*13-positive individuals from each self-described ethnic grou p was selected our of a pool of 82,979 unrelated individuals, providing at least an 80% probability of detecting a rare allele that occurred at 1%. Th ese 815 samples were subjected to allele-level SSOP typing and/or DNA seque ncing which identified 11 different: DRB1*13 alleles. DRB1*1301 and DRB1*13 02 were the most. common alleles seen in the five major ethnic groups while DRB1*1304 was not detected among Caucasians and DRB1*1305 was not detected among African Americans. DRB1*13 allele diversity was surprisingly more li mited among African Americans compared to both Caucasians and Asian/Pacific Islanders. To determine the extent of DRB1*13-DRB3 associations, 504 of th ese samples ex pressing only one DRB3-associated DRB1 allele were subjected to PCR-SSOP typing and 14 DRB1*13-DRB3 haplotypes were detected. The distr ibution revealed that African Americans were significantly different from C aucasians, Asian/Pacific Islanders, and Hispanics. Allele frequency studies such as this further support previous findings that the distribution of HL A types can differ significantly among different ethnic populations. (C) Am erican Society for Histocompatibility and Immunogenetics, 1999. Published b y Elsevier Science Inc.