Occurrence of precipitating antibody in patients with transfused hereditary ninth component of complement (C9) deficiency.

Immune Complex Glomerulonephritis in a Pregnant Woman with Congenital C9 Deficiency.

“…Because C9-defective serum demonstrates only about one-third the normal level of total complement activity (CH50), it may be difficult to detect C9 deficiency in routine assays of the complement system. Family studies have shown that C9 deficiency is inherited as an autosomal codominant trait (3,4,7,8). To date, several cases with this defect have been identified in Japan (3)(4)(5)(6) and in the U.S.A. (7,8).…”

“…Family studies have shown that C9 deficiency is inherited as an autosomal codominant trait (3,4,7,8). To date, several cases with this defect have been identified in Japan (3)(4)(5)(6) and in the U.S.A. (7,8). Epidemiologic studies indicate that there is a high frequency of C9 deficiency in Japan (approximately 0.1%), although manyindividuals who have this defect appear to be healthy.…”