HLA DQ beta restriction fragment length polymorphism and rheumatoid arthritis. Association between DQw7 and rheumatoid arthritis in DR4-positive subjects.

Two variants of the HLA-DR4-linked DQw3 allele, namely DQw7 and DQw8, were analysed in patients of mixed ancestry (Cape Coloureds) with rheumatoid arthritis and in healthy individuals from the same population group using a DQ beta-specific cDNA probe. The DQw7 allele, identified by 3,4 kb Hind III or 3,7 kb and 6,9 kb Bam HI DQ beta-specific restriction fragments, was expressed in 93% of DR4-positive patients (N = 15), compared with 12.5% DR4-positive normal individuals (N = 8). This DQ variant showed a highly significant association (relative risk = 98; P less than 0.0001) with rheumatoid arthritis in this population group and may play a role in their susceptibility to this disease.