Abstract
A patient with hereditary angio-oedema (HAO) developed mesangiocapillary glomerulonephritis (MCGN) under observation. HAO is characterized by an inherited defect of complement-deficiency of C1 esterase. MCGN is often associated with another complement abnormality which leads to depression of serum C3 and there is some evidence that the complement abnormality precedes the nephritis. The coincidence of these two rare diseases in the present patient, and in one previously described, suggests that other complement abnormalities may predispose to the development of MCGN.