Properdin factor B (Bf) polymorphism: Subtyping of SS phenotypes

The authors have studied the genetic polymorphism of the properdin factor B (Bf) by the isoelectrofocusing technique. The SS phenotypes, all similar on agarose gel electrophoresis, were shown to be heterogeneous after isoelectrofocusing; this heterogeneity corresponds to the expression of two new suballeles SA and SB, inherited in a codominant manner. Gene frequencies for 121 individuals with SS phenotype are 0.57 for SA, and 0.43 for SB.