Studies of relatives of patients with systemic lupus erythematosus

A study of 44 relatives of 19 patients with systemic lupus erythematosus showed that 11 per cent had clinical evidence of a collagen disease. The sera of one third of the asymptomatic relatives contained rheumatoid factor, while the incidence of hypergammaglobulinemia, biologic false positive tests for syphilis and antinuclear antibodies was lower but significantly greater than in the control population. Three quarters of the patients had at least one relative with clinical and/or laboratory abnormalities.