An immunogenetic study of older age onset rheumatoid arthritis.

Thirty-two patients with older age onset rheumatoid arthritis (ORA), defined as disease onset after age 60, were selected for HLA typing. The majority (69%) were rheumatoid factor (RF) seronegative. An increase in HLA-DR4, though not statistically significant, was seen in ORA (38% vs 17% normals). This antigen was strongly associated with RF seropositivity (70%, p less than 0.01) and rheumatoid nodules (75%, p less than 0.01) in ORA. We conclude that the immunogenetics of ORA are similar to that described for adult RA in general.