Race Linked to Genetic Markers
CHRISTOPHER WINDHAM
Wall Street Journal, 02/01/2005
In the latest study to wade into the question of whether race is a biologically based category or a socially constructed label, scientists at Stanford University claim to have found that 326 genetic 'markers' -- segments of DNA -- can be used to cluster people into four groups, with each group corresponding to common racial categories: white, African-American, East Asian and Hispanic.
For more than a decade some geneticists and anthropologists have argued that race isn't biologically real and therefore shouldn't be used in medical research and clinical practice. The argument is based on the fact that, for
thousands of years, humans have been marrying and having children with people of different ancestry, with the result that everyone's genes come from the same big, humanwide pool.
The mapping of the human genome and growing interest in race-based pharmaceuticals have stirred the debate in recent years.
The study, published in the February issue of the American Journal of Human Genetics, involved 3,636 people enrolled in a large trial on the genetics of hypertension. To see whether genetic markers correspond to the standard racial categories, the scientists first analyzed the volunteers' DNA, identifying which genetic markers they carried. They then used a computer program to cluster people based on genetic similarities; those who shared genetic markers were grouped together. Finally, the scientists compared those groupings with the volunteers' self-identified race. The result: people who considered themselves white had been grouped by the computer, based on their genetic markers, in one cluster, while people who consider themselves African-American had been grouped in a second, different cluster. The same held for Hispanics and East Asians. Only five people had DNA that matched an ethnic group different than the racial or ethnic box they checked at the outset of the
study.
"People have argued that race and ethnicity are purely social categories," says Neil Risch, the study's lead author, who is director of the Center for Human Genetics at the University of California, San Francisco. "We've shown that socially defined ethnic categories correspond with genetic categories." The findings are convincing because of the large number of genetic markers -- 326 -- used to cluster the participants, he says.
The study of the relationship between race and genetics largely is viewed in the medical community as a way to better understand why some ethnic groups suffer and die disproportionately from certain illnesses than others. It also could help physicians predict which patients might respond better to certain drugs, geneticists say.
But using random genetic markers to show links to ancient geographic ancestry doesn't reveal much about how such markers might be predictive in disease, says geneticist J. Craig Venter, who led the private effort to sequence the human genome and is part of the J. Craig Venter Institute. The markers aren't actually genes, but merely segments of DNA whose function is unknown.