Distribution of HLA-A alleles in eight ethnic groups from Pakistan.

The extreme polymorphism found at some loci of the HLA system has made it an invaluable tool for population genetic analyses. In this study eight diverse ethnic groups from Pakistan were analyzed at the HLA-A locus using sequence specific primers for polymerase chain reaction (PCR-SSP) and then further typed to the allele level using a two-stage sequence specific oligonucleotide probe (SSOP) strategy. Four of these ethnic groups (Burusho, Hazara, Kalash, Pathan) were from the north and four (Baloch, Brahui, Sindhi and Parsi) were from the south of Pakistan. Nine alleles were identified as unique to a particular ethnic group within Pakistan. Maximum variation was seen in the HLA-A*02 allele family for which 11 alleles were detected in the eight Pakistani ethnic groups. The alleles that showed significant variation between the Pakistani ethnic groups include A*0101, A*0206, A*0209, A*0207, A*0217, A*1101, A*2402/09 N/11 N, A*2902, A*3301 and A*3001. A phylogenetic tree based on DA distances for HLA-A allele frequencies separated the Pakistani populations from other world populations and also separated the only Dravidian speaking population of Pakistan, the Brahui, from the remaining Indo-European speaking ethnic groups of Pakistan.