[Factor 13 B (FSF) polymorphism in the Swiss population, with reference to European frequency gradients].

Phenotype and allele frequencies of the coagulation factor 13 B (FSF B) of three Swiss populations (Northern Switzerland, upper Rhone valley and valley of Safien) have been determined after electrophoresis and passive immunoblotting and are discussed with respect to the geographical distribution and to the history of these populations. The populations of the upper Rhone valley and the valley of Safien reveal a closer genetical relationship obviously due to the migration of the antecedents of the recent Safier from the Rhone valley to the Safien valley from the 13th to 14th century. The allele frequencies of the Swiss German population fit rather well the North-South genetical cline which has to be considered in the light of the early settlement of Central Europe and of the numerous migrations thereafter.