HLA DR4 and B27 antigens in familial and sporadic rheumatoid arthritis.

We studied HLA antigens in 105 unrelated American Caucasian patients with rheumatoid arthritis (RA), 70 of them with familial disease. HLA-DR4 was observed in 71% of familial RA, 63% of non-familial RA, and 27% of normal controls, confirming the already well-established association between HLA-DR4 and both familial and non-familial RA. HLA-B27 was present in 14.3% of patients, versus 8% of normal controls (p = 0.04), and was not more common in familial (10 of 70, or 14.3%) versus non-familial (5 of 35, or 14.3%) disease. These results are compared with those observed in Scandinavian patients.