HLA and rheumatoid arthritis in the Japanese.

Sixty-three Japanese patients with rheumatoid arthritis (RA) were typed for HLA-A, -B, and -DR locus specificities. A significant association was found only with increased frequency of HLA-DR4 in the patients (71.4%) compared with controls (41.8%) (corrected P = 0.007, relative risk = 3.5). No association was found with HLA-A9 or HLA-Bw54, which are in linkage disequilibrium with HLA-DR4 in the Japanese. The association between HLA-DR4 and RA observed in these Japanese patients has also been demonstrated in the white population.