Lupus-Erythematosus-like Syndrome with a Familial Defect of Complement

Abstract

Two siblings had illnesses consisting of combinations of fever, skin lesions, vasculitis, arthralgia and glomerular deposits that suggested lupus erythematosus (LE) or a similar connective-tissue syndrome. One other sibling had died of similar findings at the age of 12. Neither patient had any evidence of antibodies against DNA or other nuclear material. These patients were found to have abnormally low levels of the first component of complement, even when their disease was quiescent. Other complement components, usually seen to be depressed in LE, were consistently normal. This appears to be a hereditary defect in the first component of complement, to which the pathologic process is related. The need for nonspecific assays is indicated by the fact that the defect was missed on testing with the more common but limited β1c determination.