Histocompatibility antigens (A, B, C, and DR) in Arabs with rheumatoid arthritis.

Eighty-five Arab patients in Kuwait with classical and definite rheumatoid arthritis were typed to examine the frequency of HLA-A, B, C, and DR antigens. The results showed a significant increase in the frequency of HLA-A10, B8, B21, and DR3 antigens when compared to an age- and sex-matched control population. HLA-DR3 was present in 34 per cent of the patients compared with 2 per cent of the controls (p less than 0.001). The association of RA in the Arab population with HLA-DR3 rather than HLA-DR4 or HLA-DR1 as reported in other ethnic groups emphasizes further the complexity of the genetics of RA.