Improved coagulation factor XIII B (FXIIIB) phenotyping after neuraminidase treatment of plasma and first description of the FXIIIB 2 phenotype.

The genetically determined polymorphism of the B subunit of the human coagulation factor XIII (FXIIIB) was investigated by an improved technique of immunofixation agarose gel electrophoresis (IAGE). Employing neuraminidase (CPN) treatment of fivefold-concentrated fresh plasma and monospecific anti-human FXIIIB antiserum an excellent resolution of phenotypes was possible. Six phenotypes, FXIIIB 1,2-1,2,3-1, 3-2 and 3 were detected among 178 unrelated blood donors from Hessen, Germany, the FXIIIB 2 homozygote for the first time. Our findings confirm the 'reduced' two-allele-model of Kera et al. [10]. For the first time the allele frequencies were determined in a European population: FXIIIB*1 = 0.708, FXIIIB*2 = 0.109, FXIIIB3* = 0.183. As in family studies no unexpected phenotypes were observed in the offspring, FXIIIB might become a useful genetic marker in paternity testing, the single exclusion chance for non-fathers being 23.7%.