HLA-DR4-DQw8, but not DR4-DQw7 haplotypes occur in Indian patients with rheumatoid arthritis.

The distribution of HLA class II antigens in the Asian Indian patients with rheumatoid arthritis (RA) was studied in the present investigation. The results demonstrated that DR4 was significantly increased in both northern (chi 2 = 36.9, P less than 0.00001) as well as southern Indian (chi 2 = 17.3, P less than 0.0001) patients. HLA haplotype analysis revealed the presence of B17-DR4 among southern Indians. Amongst northern Indians, four DR4 haplotypes occurred significantly: A1,B17,DR4; A19,B7, DR4; A30,B13,DR4; and A33,B44,DR4. An analysis of TA10 and DQ'Wa' specificities revealed that all the DR4-DQw3 positive northern Indian RA patients were DQw8 as compared to its frequency of 33.3% in controls. A positive association observed between DR4-DQw7 and RA in some western Caucasian populations was not present in this series. A group of three DR4 positive RA patients were found to be DQw3 negative and DQ'Wa' or DQw4 positive. These results indicated that susceptibility to RA may be controlled by genes in the DR locus independent of any DQ associations.