Factor B polymorphism in four Asian populations: Electrophoretic characterization of a subtype of "F" and of new variants in the Chinese

The genetic polymorphism of factor B (BF) in four Asian populations was studied by immunofixation after agarose gel electrophoresis (AGE) in both veronal buffer (VB) and Tris/glycine/veronal buffer (TGVB). A suballele of the BF*F and three rare alleles were detected in a Chinese population. The subtype and the rare variants were further characterized by using isoelectric focusing in polyacrylamide gels (PAGIF) and by zymosan treatment of the serum samples. The subtype was identified as BFFb1, first defined in the Japanese and found to occur at a polymorphic frequency. One of the rare variants exhibited an intermediate mobility between BFF and BFS and seemed to be similar to BFF025. PAGIF, however, could clearly discriminate the two variants that had a similar mobility on AGE. The results obtained in this study suggest that conventional electrophoresis is not enough to characterize a new variant and to discriminate it from previously reported variants. The findings obtained on immunofixation after AGE/TGVB and in PAGIF must be added to those obtained by the standard method.