Membranous nephropathy in a patient with hereditary complete complement C4 deficiency

Abstract
Hereditary complete deficiency of complement C4 is an extremely rare condition. Fewer than 30 cases have been reported so far. Because C4 exists in two isoforms, C4A and C4B, whose genes lie on chromosome 6 in the MHC class III region, complete deficiency requires a defect in all four C4 genes. In the majority of patients this is caused by homozygocity for a C4AQ0C4BQ0 haplotype (HLA A24 B38 Cw7 DR13 DQ6 in our patient).