Familial C1q deficiency in 3 siblings with glomerulonephritis and Rothmund-Thomson syndrome.

Complete absence of C1q was demonstrated in the sera of 3 siblings in association with renal and cutaneous lesions. The serologic findings were consistent with an autoimmune disorder. Hematuria was the renal symptom present in all 3 patients; proteinuria was also present in 1. Renal biopsies showed mesangial proliferative glomerulonephritis with diffuse glomerular deposits of IgM and C3 in all cases. Clinical cutaneous manifestations and the histological picture were those of the Rothmund-Thompson syndrome. Three combined diseases, characterized by renal and cutaneous affection and serologic abnormalities, are presented in this paper.