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. BF*F allele was splitted into two suballeles, named BF*FA and BF*FB. 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. BF*FB may be a susceptibility suballele to IMN rather than BF*FA.