Factor B subtypes in Japanese patients with IgA nephropathy and with idiopathic membranous nephropathy.

The present paper describes a method of subtyping of properdin factor B (BF) using polyacrylamide gel isoelectric focusing followed by immunoblotting, and the distribution of BF subtypes in Japanese patients with IgA nephropathy or idiopathic membranous nephropathy (IMN) along with controls. BFF allele was splitted into two suballeles, named BFFA and BFFB. There were significant differences in the BF suballele frequencies between the IMN patient group and the control group. A significant association of IMN with the BF FA subtype (p less than 0.05) and with the BF FB subtype (p less than 0.001) was also found. BFFB may be a susceptibility suballele to IMN rather than BF*FA.