We analyzed data from 300 nonrelated self-identified Mestizo individuals from 6 states located in geographically distant regions in Mexico: Sonora (SON) and Zacatecas (ZAC) in the north, Guanajuato (GUA) in the center, Guerrero (GUE) in the center– Pacific, Veracruz (VER) in the center–Gulf, and Yucatan (YUC) in the southeast. Considering that Zapotecos have been shown as a good ancestral population for predicting Amerindian (AMI) ancestry in Mexican Mestizos (16), we included 30 Zapotecos (ZAP) from the southwestern state of Oaxaca (Fig. 1). For comparative purposes, we included similar data sets from HapMap populations: northern Europeans (CEU), Africans (YRI), and East Asians (EA), including Chinese (CHB) and Japanese (JPT).As expected, Mestizo admixture is mainly between Caucasoids and Amerindians, with a very little Sub-Saharan African thrown in at the individual level. Moreover, as with many populations, such as the Uyghur, where admixture took place several generations ago, individual admixture levels are fairly uniform, with very few individuals deviating strongly towards either the Caucasoid or Amerindian end of the spectrum.
The variation in individual admixture appears only somewhat stronger than in the Uyghur, which may be explained either by the smaller number of markers used here, making the assessment of admixture "noisier", or alternatively might be the result of the fact that admixture in Mexican Mestizos happened more recently, and immigration into the Americas from Europe continued hence, hence the homogenization of the population is still ongoing.
Table S1 from the Supplementary material (pdf) shows the exact admixture proportions in the studied Mestizo populations and the HapMap populations.
Analysis of genomic diversity in Mexican Mestizo populations to develop genomic medicine in Mexico
Irma Silva-Zolezzi et al.
Mexico is developing the basis for genomic medicine to improve healthcare of its population. The extensive study of genetic diversity and linkage disequilibrium structure of different populations has made it possible to develop tagging and imputation strategies to comprehensively analyze common genetic variation in association studies of complex diseases. We assessed the benefit of a Mexican haplotype map to improve identification of genes related to common diseases in the Mexican population. We evaluated genetic diversity, linkage disequilibrium patterns, and extent of haplotype sharing using genomewide data from Mexican Mestizos from regions with different histories of admixture and particular population dynamics. Ancestry was evaluated by including 1 Mexican Amerindian group and data from the HapMap. Our results provide evidence of genetic differences between Mexican subpopulations that should be considered in the design and analysis of association studies of complex diseases. In addition, these results support the notion that a haplotype map of the Mexican Mestizo population can reduce the number of tag SNPs required to characterize common genetic variation in this population. This is one of the first genomewide genotyping efforts of a recently admixed population in Latin America.