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.