Analysis of mtDNA and Y-chromosome haplogroups in Mexican Mestizos and Amerindian groups. I. Silva-Zolezzi1, B. Z. Gonzalez-Sobrino2, J. K. Estrada-Gil1, A. Contreras1, J. C. Fernandez1, E. Hernandez-Lemus1, L. Sebastian1, F. Morales1, R. Goya1, C. Serrano2, G. Jimenez-Sanchez1 1) National Institute of Genomic Medicine, Mexico; 2) Anthropological Research Institute, UNAM, Mexico.

   The Mexican population is mainly conformed by Mestizos, individuals with a genetic background consisting of Amerindian, European and African contributions. Genetic heterogeneity in Mexicans results from a complex demographic history that started with the peopling of North and Central America about 15,000 yrs ago, including the settlement of at least 60 different indigenous groups in Mexico, regional differences in admixture dynamics after colonization by Spaniards in the XVI century, epidemics and migration. Y chromosome-specific and mitcohondrial (mt) DNA polymorphisms are useful to help understand the genetic structure and history of human populations, due to their uniparental inheritance and lack of recombination. In order to refine the portrait of genetic variability derived from the Mexican Genome Diversity Project, we are characterizing maternal and paternal lineages participating in admixture. For this we included genotypic data from 163 mt SNPs and 123 Y chromosome SNPs present in the Illumina Human1M chip of 450 individuals, 300 mestizos from six states located in different regions: Northern, Central and Southern; and 150 individuals from different Amerindian groups (Tepehuanes, Zapotecos and Mayas). With this information, we are measuring genetic diversity using Fst and AMOVA analysis. Admixture analysis includes average and individual ancestral contribution estimates using autosomal SNPs. Initial results show that in our Mestizo sample, 88% of the mt haplogroups are Amerindian (A, B, C or D), and the rest includes European and African lineages. We have identified differences in proportions of each haplogroup in both Mestizos and Amerindians. Knowledege about the distribution of mt and Y-chromosome haplogroups in Mexican Mestizos and Amerindian groups, will generate valuable information to better understand genetic relationships between Mexicans and other Latin American populations. In addition, it may contribute to strengthen analysis in association studies of common complex diseases.