Associations between HLA class II alleles in a North Indian population

The HLA DR and DQ class II genes are in strong linkage disequilibrium and recombination is quite rare. However, many different DR-DQ haplotypes appear to have developed during evolution, giving rise to a variety of combinations with different distributions in populations. In the present report, 138 subjects from North India were studied for the alleles of HLA-DRB1, DRB3, DRB5, DQB1 and DQA1 loci using PCR-oligotyping. The probable haplotypes were constructed based on two-locus associations observed in this population. A frequent haplotype in this population, DRB1(*)1501-DRB5(*)0101-DQA1(*)0103-DQB1(*)0601, has been reported very rarely in other ethnic groups. Other DR2 haplotypes, like DRB1(*)1502-DRB5(*)0102-DQA1(*)0103-DQB1(*)0601, earlier reported in Caucasians, Chinese and Latin Americans, and DRB1(*)1502-DRB5(*)0102-DQA1(*)0103-DQB1(*)0503, earlier reported in Gypsies, were also observed. A relatively rare haplotype in Caucasians which was earlier reported in Gypsies from the Czech Republic, DRB1(*)1404-DRB3(*)0202-DQA1(*)0101-DQB1(*)0503, was observed frequently in Indians, suggesting the probable migration of Gypsies from India. The results suggest that the North Indian population contains a mixture of Caucasoid, Black and Chinese genes. Similarities with Gypsies and South-East Asian populations suggest the role of ancient migrations from India.