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Many Brazilians have a mixed racial background that makes developing medication difficult. Image courtesy of Flickr user robonline

“At my age and with so much mixed blood I no longer know for sure where I belong.  Nobody knows it in these lands … and I believe it will take centuries to know it,” Colombian writer Gabriel Garcia Marquez once wrote. He was referring, of course, to the mixing of genomes that took place in Latin America after the arrival of European colonists and the rise of the African slave trade in the 15th century.

While racial identity is a touchy subject in just about any country, understanding the genetics of mixed populations is becoming a key issue as we discover how drugs can interact with an individual’s genetic makeup. Appropriately, Marquez was quoted by a Brazilian geneticist with a half-German half-Spanish name, Guilherme Suarez-Kurtz, at the 1st Latin American Pharmacogenomics and Personalized Medicine Congress here in Puerto Rico.

During a riveting talk yesterday, he explained how three of the “colors” listed on Brazil’s census forms—white, brown, and black—had a limited relationship with an individual’s genetic background. For instance, Brazilians who labeled themselves “black” ranged from having less than 5 percent to more than 90 percent European ancestry based on their DNA. Such variation becomes important because different populations possess variants of genes that influence how well they are able to metabolize drugs, which impacts the drugs’ effectiveness and, potentially, their safety.

Unfortunately, most of the world’s drugs have been tested primarily on Caucasian populations. Suarez-Kurtz argues that running clinical trials on “admixed” populations in Latin America could be of wider relevance. Other talks examined the level of admixture in different Mexican and Puerto Rican populations, and geneticists are working overtime to understand what this complex heritage means for the future of medicine.

In fact, an organization called PGENI, PharmacoGenetics for Every Nation Initiative, has even sprung up to help developing nations select essential drugs that match their country’s genetic makeup. Kevin Long, the organization’s information guru, told me it is still too expensive to provide personalized medicine to everyone today, but “population-ized” medicine is already becoming a reality.

Brendan Borrell will be guest blogging this month. He lives in New York and writes about science and the environment; for Smithsonian magazine and Smithsonian.com, he has covered the ecology of chili peppers, diamonds in Arkansas and the world’s most dangerous bird.