Genetic heterogeneity of the B subunit of coagulation factor XIII: resolution of type 2

An apparent discrepancy in phenotyping the genetic polymorphism at the FXIIIB locus by electrophoresis or isoelectric focusing has been investigated. The data indicate that the product of the type 2 allele, which can be detected by agarose electrophoresis, is not resolved from the product of the type 1 allele by isoelectric focusing. The understanding of this problem has previously been confused by the absence or very low frequency of the type 2 allele in Japanese populations studied by isoelectric focusing and electrophoresis. An alternative enzyme-linked immunoblotting technique is described which substantially improves the method for phenotyping products of the FXIIIB locus after electrophoresis.