Imagine if people in Kansas and California were genetically distinct from each other as someone from Germany is someone from Japan. That's the kind of remarkable genetic variation that scientists have now found in Mexico, thanks to the first detailed study of human genetic variation in this country. This local diversity could help researchers trace the history of the different indigenous peoples of the country and help them develop better diagnostic and medical treatment tools for people of Mexican origin living around the world.
The team has done a "tremendous job" creating a "map of all the genetic diversity in Mexico," said Bogdan Pasaniuc, population geneticist at the University of California (UC), Los Angeles, who was not involved in the research.
Mexico contains 65 different indigenous ethnic groups, 20 of which are represented in the study, said Andres Moreno Estrada, a geneticist of the population in Stanford University in Palo Alto, California, and lead author of the study. Working with Carlos Bustamante, a geneticist other population Stanford, the team sampled the genomes of indigenous people throughout Mexico, in the desert of northern Sonora in the Chiapas jungle in the south. over the centuries of life so distant and often in isolation because of mountain ranges, vast deserts, or other geographical barriers, these people have developed genetic differences from one other, Bustamante said. Many of these variants are what he calls "rare in the world, but locally common." In other words, a genetic variant is widespread in an ethnic group, as the Mayans, may almost never occur in people of different ancestry as people of European descent. If you study the genomes of Europeans alone, you'd never catch the Maya variant. and that's a big problem for people with Mayan descent if this variant increases their risk of disease or changes how they react to different types of drugs. "All politics is local, right? what we are beginning to find is that many of genetics is local, too," Bustamante said.
When the team analyzed the genomes of 511 indigenous people from across Mexico, they found a remarkable amount of genetic diversity. The most divergent indigenous groups in Mexico are as different from each other that Europeans are East Asians, they report online today in Science . This diversity maps the geography of Mexico itself. Most ethnic groups live distant from each other, more various of their genomes appear to be.
But most people in Mexico or of Mexican origin these days are not indigenous, but mestizo, which means they have a mix of native ancestry, European and African. Is their genomes also vary by which region of Mexico where they come from or whatever the local variation was smoothed by centuries of various group meetings, mixing, and having babies?
To answer this question, the team collaborated with the Mexican National Institute of Genomic Medicine, which was genetic data collection mestizos for many years. Somewhat surprisingly, they found that mestizos in a given part of Mexico tend to have the same genetic variants "rare" than their native neighbors. The genomes of mestizo "track so well with Aboriginal groups that we could use genetic diversity in mestizos to make inferences about [their native] ancestors," said Pasaniuc. Strong genetic markers of Mayan descent, for example, appear in the genomes modern people living in the Yucatan Peninsula and the northern part of the Gulf coast of Mexico in the modern state of Veracruz, which probably reflects a trade or way of pre-Columbian Maya migration. "this gives us an understanding of history what these people were up to, "says Christopher Gignoux, a postdoc in the group of Bustamante at Stanford.
Even more important are the clinical implications of the study. to determine whether genetic variation Mexico could influence the risk of disease and the accuracy of diagnostic tools, Esteban Burchard, a lung specialist at UC San Francisco, analyzed how a common measure of lung function tracks with the genetic variation of Mexico. It found that people with common genetic variants in the east of the country have had different results on the lung function test compared with people with western variants. This means that doctors probably should not use the same criteria to diagnose lung diseases in both populations, he said. "What we have shown that, depending on the type of Amerindian descent you have, it can significantly influence the diagnosis of lung disease, in a good or bad way," says Burchard.
The function lung is just one example of how fine-scale genetic variation of Mexico could affect the disease and diagnosis, the team said. for Bustamante, this wealth of potential clinical applications has been particularly exciting study to be a part of. "let's move beyond the issues that we tend to focus on population genetics and really try to address how we will think about the translation of this" so that modern people can benefit.
* Correction, June 13, 11:28: Mexico contains 65 different indigenous ethnic groups, not 55, as was previously indicated. This has been corrected.
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