Racial groupings match genetic profiles, Stanford s...( ntative of racial/ethnic groups through...)

For each person in the study, the researchers examined 326 DNA regions that tend to vary between people. These regions are not necessarily within genes, but are simply genetic signposts on chromosomes that come in a variety of different forms at the same location.

Without knowing how the participants had identified themselves, Risch and his team ran the results through a computer program that grouped individuals according to patterns of the 326 signposts. This analysis could have resulted in any number of different clusters, but only four clear groups turned up. And in each case the individuals within those clusters all fell within the same self-identified racial group.

"This shows that people's self-identified race/ethnicity is a nearly perfect indicator of their genetic background," Risch said.

When the team further analyzed each of the four clusters, they found two distinct sub-groups within the East Asian genetic cluster. These two groups correlated with people who identified themselves as Chinese and Japanese. None of the other genetic groups could be broken down into smaller sub-sections. This suggests that there isn't enough genetic difference to distinguish between people who have ancestry from northern Europe versus southern Europe, for example. Risch admitted that few people in this study were of recent mixed ancestry, who might not fall into such neat genetic categories.

This work could influence how medical research is carried out. Often researchers ask study participants to identify their race and ethnicity at the beginning of a clinical trial. The researchers can then follow people of different racial/ethnic groups to see which group is more likely to get a particular disease or respond well to a new treatment. This information can help future doctors know which
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Contact: Amy Adams
amyadams@stanford.edu
650-723-3900
Stanford University Medical Center
27-Jan-2005