Factor B polymorphism in North American blacks: study of a new variant Bf F1.35

A "new" variant of the factor B (Bf) system has been found in the serum of three individuals of a North American Black family. This variant migrates faster than Bf F1 and has been designated Bf F1.35 on account of the relative electrophoretic mobility using reference Bf typed sera. This new factor B variant (F1.35) was found to be functionally active using a specific hemolytic overlay technique and was inherited on an HLA-A28;Bw35;C4 A3,B1;C2C;DR3;GLO2 haplotype.