The etiology of rheumatoid arthritis has not been fully understood. Genetic factors have been pointed out to be involved in pathogenesis of RA because of many clinical and experimental facts. In this report, first we studied intrafamiliar accumulation of RA by the questionaire for 314 RA patients receiving treatment in our hospital. Patients with intrafamiliar accumulation were found in the frequency of 22 percent of all, and these patients tend to show onset at younger age than patients without intrafamiliar accumulation.
HLA typing was performed for 17 RA patients whose parents or children suffered from RA. 13 patients (76.5%) of them have HLA-DR4 antigen.
