May 8, 2010

Latino Genetic Ancestry

A pretty paper was published recently about Latino Genetic Ancestry, in the Proceedings of the National Academy of Sciences The researchers analyzed 100 individuals of Ecuador, Colombia, Puerto Rico and the Dominican Republic, the largers minorities between hispanics in NYC...the capital of the world! Currently, Hispanc/Latino Americans comprises 15% of the USA population, or aprox. 47 million people, the largest minority in all the country.
They have cited one of our papers published on Genetic Admixture of Ecuadorians. The title of the paper is: Genome-wide patterns of population structure and admixture among Hispanic/Latino populations. As expected, coinciding with our study in Ecuador and Colombia, the study found that Latino populations differ markedly in the contribution of the source populations. In Ecuador and Colombia, there is typically little African contribution to ancestry, and most individuals are genetic admixes of European and Native Amerindians. But in the Caribbean locations of Puerto Rico and the Dominican Republic, at the western reach of the African slave trade, people typically include substantial African ancestry.

Hispanic/Latino populations possess a complex genetic structure that reflects recent admixture among and potentially ancient substructure within Native American, European, and West African source populations. Here, we quantify genome-wide patterns of SNP and haplotype variation among 100 individuals with ancestry from Ecuador, Colombia, Puerto Rico, and the Dominican Republic genotyped on the Illumina 610-Quad arrays and 112 Mexicans genotyped on Affymetrix 500K platform. Intersecting these data with previously collected high-density SNP data from 4,305 individuals, we use principal component analysis and clustering methods FRAPPE and STRUCTURE to investigate genome-wide patterns of African, European, and Native American population structure within and among Hispanic/Latino populations. Comparing autosomal, X and Y chromosome, and mtDNA variation, we find evidence of a significant sex bias in admixture proportions consistent with disproportionate contribution of European male and Native American female ancestry to present-day populations. We also find that patterns of linkage-disequilibria in admixed Hispanic/Latino populations are largely affected by the admixture dynamics of the populations, with faster decay of LD in populations of higher African ancestry. Finally, using the locus-specific ancestry inference method LAMP, we reconstruct fine-scale chromosomal patterns of admixture. We document moderate power to differentiate among potential subcontinental source populations within the Native American, European, and African segments of the admixed Hispanic/Latino genomes. Our results suggest future genome-wide association scans in Hispanic/Latino populations may require correction for local genomic ancestry at a subcontinental scale when associating differences in the genome with disease risk, progression, and drug efficacy, as well as for admixture mapping.

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