HLA class II DR, DQ, and DP restriction fragment length polymorphisms in rheumatoid arthritis.

HLA class II restriction fragment length polymorphisms (RFLPs) were studied in 43 individuals with established seropositive rheumatoid arthritis (RA) and in a group of healthy controls. All patients and controls were tissue typed for HLA-A, B, and DR antigens. Rapid, initial screening for RA associated RFLPs was conducted by pooling DNA samples from 11 HLA-DR4 positive patients with RA and comparing the RFLP patterns with those seen in a pool of DNA samples drawn from 11 HLA-DR4 positive healthy controls. Candidate RA associated RFLPs were examined in our full panel of patients with RA and controls. In most cases the RFLPs detected showed no significant association with RA. An exception was a 13.0 kb DraI DQ beta associated RFLP, which, when HLA-DR4 positive patients with RA and controls were considered alone, showed a weak positive association with susceptibility to RA. This RFLP was not associated with known DR, DQ, or Dw specificities. These results show a distinct paucity of class II RA associated RFLPs but may indicate a role for DQ beta genetic variation in the aetiology of RA.