PI, GC, HP, and TF serum protein polymorphisms in Siena, Tuscany, Italy, with a review of data for Italy.

The genetic polymorphism of four serum proteins (PI, GC, HP, and TF) is analyzed in a sample of 200 unrelated individuals from the province of Siena, Tuscany, central Italy. Siena is traditionally divided into 17 Contrade, that act as social units. The aim of this report is to ascertain whether this peculiar organization has led to genetic differentiation among the inhabitants of each Contrada and from other populations of Italy. For this purpose, the frequencies of genetic markers found in Siena are also compared with those reported for the same serum proteins in Italy based on provincial samples from the literature. The statistical analyses (heterozygosity estimates, F-statistics, and cluster analysis) suggest that the Contrade represent only a cultural and historical institution without biological consequence and that the Italian population can be considered genetically homogeneous