Analysis of polymorphic loci of Huntington genes in peoples from the Volga-Ural region

Eleven populations of the Volga-Ural region were analyzed with respect to three intragenic polymorphisms of the Huntington disease gene (IT15), including highly polymorphic (CAG)n and moderately polymorphic (CCG)n of exon 1 and neutral del2642 of exon 58. In the case of (CAG)n, 101 genotypes were observed, with genotype number varying from 15 in Southeastern Bashkirs to 34 in Mari. Allele diversity RS ranged from 9.70 in Southeastern Bashkirs to 18.00 in Chuvash, averaging 13.79 +/- 2.12. The (CAG)n allele frequency distribution was unimodal and had a maximum at (CAG)17. In the case of (CCG)n, six alleles with 6-10 or 12 repeats were observed. RS was 4.13 +/- 0.44, ranging from 3.73 in Udmurts to 4.99 in Tatars. In the case of del2642, allele del- was detected at a frequency 0.830 in Mari to 0.932 in Udmurts. Of all Volga-Ural ethnic populations, Finno-Ugric ones proved to be most heterogeneous with respect to the three polymorphisms, whereas Turkic populations and, in particular, Bashkirs were homogeneous. Micro-differentiation of the Volga-Ural populations corresponded to the European type.