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Hispanic and Latino genetic background diverse, yet telling

Population geneticist Carlos Bustamante, PhD, doesn't have a time machine. But even without one he's managed to peek into the genetic pasts of various ethnic and racial groups. Figuring out who came from whom, and in what proportions, is important to understand not just human history, but also when calculating group-based disease risk and drug efficacy.

Now he's found that Hispanics and Latinos - a catch-all name for a group whose members hail from nearly anywhere in Latin America - are a genetic amalgamation of Native Americans, Europeans and West Africans. But their specific proportions vary according to the country from which their ancestors hail:

There is no one genetic fingerprint for members of the Hispanic/Latino group. They are extremely complex. But we've found that we can look at an individual's genome and predict which country they or their ancestors came from.

The work was published this week in the Proceedings of the National Academy of Sciences. It is one of a series of articles focusing on human evolution that arose from a Sackler Colloquium in Irvine in Dec. 2009. Bustamante conducted the research while at Cornell University before coming to Stanford in January.

Specifically, Bustamante and his colleagues at Cornell and the New York University School of Medicine found that a person from Mexico or Ecuador primarily has genetic sequences indicative of a Native American and European past, while someone from Puerto Rico or the Dominican Republic has more West African sequences (most likely as a result of the area's proximity to old slave trade routes).

The researchers also found - not surprisingly - a gender bias in the regional contributions to Hispanics and Latinos. That is, the mixing occurred primarily between male Europeans and female Native Americans and West Africans.

Here's why we should care:

Our ultimate goal is to enable medical genomics on a global scale. We've previously relied on analyses that associate specific traits or disease risks with certain genetic sequences. But we've begun to learn that this doesn't do a good job of explaining all the genetic variation among humans. Furthermore, it's been limited to a small corner of the human genomic population - all the sequences are from people from North America. We want to understand the full spectrum of variation across all genomic backgrounds.

What's next? North Africans, who, as residents of a centuries-old major trading hub, may be even more diverse. Stay tuned.

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