Heterogeneity of HLA-DR2 haplotypes in Caucasoid Americans, African Americans, Chinese Americans, Native Americans and Xiamen Chinese

HLA-DR, -DQ specificities were determined by PCR amplification with SSOP in 4560 individuals: Caucasoid Americans (CA), African Americans (AA), Chines e Americans (ChA), Native Americans (NA) and Xiamen Chinese (XC). DR2 subty pes were corn pared amongst the five ethnic populations. The DRB1*1501-DRB5 *0101 haplotype was found to be the most frequent in all populations except African Americans, in which DRB1*1503-DRB5*0101 was the predominant haplot ype, accounting for 65% of DR2 subtypes. In contrast to Caucasoid Americans , the DRB1*1602 is strongly associated with the DRB5*0101 allele in Chinese populations. The presence of DRB5*0203 and DRB1*1602-DRB5*0101 haplotypes in Chinese populations, especially in Xiamen Chinese, suggests that various DR2 haplotypes may be generated via multiple gene conversion events togeth er with point mutations and reciprocal recombination. The strong DR and DQ associations are found in DRB1*1501/DQB1*0602 (66.22%) for CA, DRB1*1503/DQ B1*0602 (56.58%) for AA, DRB1*1501/DQB1*0602 (30.20%) and DRB1*1602/DQB1*05 02 (15.76%) for ChA, DRB1* 1501/DQB1*0602 (41.55%) and DRB1*1602/DQB1*0301 (40.25%) for NA, and DRB1*1501/DQB1*0602 (30.26%) and DRB1*1602/DQB1*0502 ( 25.81%) for XC.