HLA-DO-related restriction fragment length polymorphisms in rheumatoid arthritis: evidence for a link with disease expression.

Eighty-three patients with rheumatoid arthritis (RA) were investigated for HLA-DQ and DR locus restriction fragment length polymorphisms (RFLP). Of the 83 patients, 61 (73%) possessed the DR4 allele and within this group we have investigated the relative frequencies of two DQ beta gene variants of DQw3, DQw7 and DQw8, one of which we had previously found to be raised in Felty's syndrome. This analysis revealed a significantly higher frequency of DQw7 containing haplotypes in DR4 positive rheumatoid patients (64%) than in DR-matched healthy controls (42%). Furthermore, the distribution of DQw7 was biased towards those patients with greater disability indicated by the HAQ score, more systemic disease and higher titres of rheumatoid factor, suggesting that DQw7 may contribute to disease expression.