Association of HLA-DRw4 with rheumatoid arthritis in black and white patients.

The HLA-A, B, C, and DR antigens were typed in 35 black and 35 white Americans with rheumatoid arthritis. The frequency of HLA-DRw4 was increased in both the black and white patient patient groups compared to the race-matched control groups. DRw4 was found in 45.7% of the black patients compared to 14.3% of the black controls (corrected P value < 0.035) and DRw4 was found in 71.4% of the white patients compared to 40.0% of the white controls (corrected P value < 0.035). These data indicate that immunogenetic factors related to DRw4 are important in the development of rheumatoid arthritis in American blacks as well as whites.