Genetic variation among four Mexican populations (Huichol, Purepecha, Tarahumara, and Mestizo) revealed by two VNTRs and four STRs

Allele distributions of two polymorphisms with variable number of tandem re peats (VNTR), D1S80 and APOB, and four poly morphisms with short tandem rep eats (STR), VWA, TH01, CSF1PO, and HPRTB, were analyzed in three Mexican et hnic groups: Huichol, Purepecha, and Tarahumara. Genotype distribution was in agreement with Hardy-Weinberg expectations for each locus and ethnic gro up. Heterozygosity (Ei), power of discrimination, and probability of exclus ion were estimated. The three groups presented some distinctive genetic fea tures: (I) a diminished genetic diversity (H = 66.8% to 73.4%) and mean num ber of alleles by locus (5.8 to 6.3) in comparison with Mexican mestizos (H = 78.3%, 10.5 alleles/locus), and (2) uneven allele distributions as evide nced by "distinctive alleles" with high frequencies, especially in the Tara humara and the Huichol. Genetic relatedness analysis included data from a p reviously typed mestizo population, the largest and most widely distributed population in Mexico. Allele distribution differentiation was observed amo ng all four groups, except between mestizo and Purepecha (p > 0.05), which was interpreted as indicating a larger Spanish component in the Purepecha a s a result of gene flow effects. Although intrapopulation inbreeding (F-1S) was not significant, heterozygote deficiency in the total population (F-1T ) and divergence among populations (F-ST) were significant (p < 0.05). Gene tic distances displayed a closer relationship among mestizos, Purepechas, a nd Huichols in relation to Tarahumaras. Correlation between the observed ge neric features and the geographic isolation level points to genetic drift a s the main cause of differentiation among these Mexican populations.