A new method for FXIIIA genetic variants determination using isoelectric focusing in 1 M urea. Evidence for three structural gene loci, FXIIIA1, FXIIIA2, and FXIIIA3.

A new method for separating genetic variants of the A subunit of human coagulation factor XIII using ultrathin layer polyacrylamide gel isoelectric focusing in 1 M urea followed by immunoblotting is described. The pattern obtained by this method differs from that reported previously: Three sets of unrelated band patterns are observed and can be explained by the existence of two additional gene loci, designated FXIIIA2 and FXIIIA3, besides the previously reported FXIIIA locus, now renamed FXIIIA1. The FXIIIA2 locus is polymorphic and shows three commonly occurring phenotypes, FXIIIA2 1, FXIIIA2 2-I, and FXIIIA2 2. These are determined by two common alleles, FXIIIA2*1 and FXIIIA2*2, with respective frequencies of 0.7965 and 0.2035 in the Japanese population. The studied population conforms to a Hardy-Weinberg equilibrium, and family data confirmed autosomal codominant transmission. The FXIIIA3 locus is monomorphic.