Are the Basques a single and a unique population?

Different analyses of genetic polymorphisms performed on the Basque population have suggested a possible heterogeneity of the Basques and a singularity of their genetic characteristics. In this paper, both aspects are analyzed by means of the genetic study of seven polymorphic systems--ACP, ADA, AK, ESD, PGD, GC, and HP--in 854 autochthonous individuals from the province of Vizcaya. The individuals were classified as being from the regions of Arratia, Guernica, Durango, Uribe, Marquina, Lea, and Bilbao, on the basis of the birthplaces of their four grandparents. Analyses for heterogeneity of the gene frequencies distribution suggest that there is a moderate genetic heterogeneity, probably produced by centuries of geographical and administrative isolation of these regions. The comparison with caucasoid populations, performed using the principal components analysis and Cavalli-Sforza and Edwards arc distance, indicates that the subpopulations of the province of Vizcaya have experienced little genetic exchange with other caucasoids and that the distribution of their genetic frequencies differentiates them from other populations.