The distribution of F13A subtypes in four populations using agarose isoelectric focusing and Western Blot detection.

Using an isoelectric focusing gel containing agarose, urea, a separator and a narrow range ampholyte of pH 5-6, a system was designed to split the F13A*1 and F13A*2 alleles into the subtypes 1A, 1B, 2A and 2B. Four population groups (European-Americans, African-Americans, Mexican-Americans and Native-Americans) were data based. Subtyping F13A increased the information content significantly over the previous F13A typing system by doubling the number of alleles and increasing the number of phenotypes from three to ten. The new system has proved to be of value in parentage testing by increasing exclusionary power in cases of non-paternity and increasing the paternity index in non-exclusionary cases. Though there does not appear to be any significant variation among U.S. populations, published data on Japanese populations suggests that significant differences among populations may exist, leading to an anthropological usefulness as well.