A comparison of molecular HLA-DR and DQ allele profiles forming DR51-, DR52-, and DR53-related haplotypes in five ethnic Thai populations from mainland southeast Asia

Using PCR-SSOP typing we have deduced the composition and frequency of HLA- DRB1, -DRB3, -DRB4, -DRB5, -DQA1, and -DQB1 alleles present in DR51-, DR52- , and DR53-related haplotypes, in 519 individuals representative of five et hnic Thai populations recruited in central, northeastern and northern Thail and. In total, we have: unequivocally detected at varying frequencies, 17 D R51-related haplotypes, 24 DR52 haplotypes, and 12 DR53 haplotypes in the s tudy groups. We document evidence of north-south gradients of DR51-related haplotypes, whereby thr overall frequency of DR51-containing haplotypes is relatively more common in the northern Thai groups. Similarly, within DR53- related haplotypes the frequency of DRB1*0901-containing haplotypes increas es in the more northerly groups, and an inverse effect was observed with DR B1*0701-containing haplotypes that were relatively more common in the north eastern and central Thais. We have also com pared the class II haplotype pr ofiles of the Thais with the equivalent profiles reported in other non-Thai ethnic groups from mainland and insular SE Asia. One DR51-related haplotyp e DRB1*1502x, DRB5*0102x, DQA1*0101/4, DQB1*0501, would appear to be charac teristic of Thai populations, as it was the most common DR2 haplotype in al l five study groups and is also prevalent in other mainland southeast Asian s, but is much less evident in the more northern populations of eastern Asi a or China. (C) American Society for Histocompatibility and Immunogenetics, 2000. Published by Elsevier Science Inc.