The Howard researchers aren't alone at the crossroads of biological science and race.
A company called NitroMed Inc. of Bedford, Mass., is developing an experimental heart-failure drug called BiDil just for blacks. It has launched a study in 1,100 patients to follow up on prior research that indicated the drug works best in blacks. It's not clear why that's so, but NitroMed is collecting genetic data from study participants to look for clues, said CEO Michael Loberg.
Elsewhere, scientists are seeking about 1,300 black Americans with schizophrenia and 5,000 of their relatives to look for genes that predispose people to the disease. The federally funded study focuses on American blacks because the unusually wide diversity in their DNA should make locating genes easier, said Rodney Go of the University of Alabama at Birmingham, a leader of the project.
To keep all this in perspective, it helps to realize that the DNA of any two people of the same sex, no matter what race, is overwhelmingly the same. It's about 99.9 percent alike.
In fact, scientists say it's quite possible for the DNA of two people of different races to bear a stronger resemblance than that of two members of the same race. Research shows that the amount of DNA variation within a continent, such as Africa, Asia or Europe, is far greater than the variation between continents, by about 9 to 1.
The whole concept of race has been criticized by many scientists. It's merely a social invention and "biologically meaningless," a 2001 editorial in the New England Journal of Medicine declared. The American Anthropological Association in 1998 stressed that neighboring populations interbreed and that physical traits tend to vary gradually rather than abruptly over geographic areas. Moreover, one trait, such as dark skin, doesn't unerringly predict the presence of others, like hair texture, the association said.
So "any attempt to establish lines of division among biological populations (is) both arbitrary and subjective," the association said. In fact, "most of what's coming out of modern human genetics now tells us ... we are all genetically similar, and there is a tremendous degree of overlap. There aren't nice, neat categories you can put people into," says University of Utah geneticist Lynn Jorde.
But he also says there's more to the story. Scientists have identified patterns of genetic markers that can reveal a person's geographic ancestry -- a term they prefer to "race," which they say is ambiguously defined and connotes social aspects as well as biology.
Jorde, for example, has found that by looking at the overall pattern of details at 160 places in human DNA, a computer could identify whether DNA samples came from Europe, East Asia or sub-Saharan Africa. Others have made similar findings.
Some scientists, in fact, use DNA to calculate what percentage of different ancestries individuals have. Given the intermixing of populations across human history, that makes more sense than assigning people a single race, says Mark Shriver, an assistant professor of anthropology and genetics at Penn State University.
Scientists say DNA-based studies of ancestry can help them track down the underpinnings of disease and of good or bad response to medications. The big disease targets are common disorders -- high blood pressure, cancer, asthma and others -- that appear to result from environmental triggers in combination with many susceptibility genes. These genes are actually specific variants of genes everybody has, and they are devilishly hard to identify.
At Howard, a historically black private university, the 2-year-old National Human Genome Center focuses on how DNA and the environment interact in disease susceptibility and treatment in black Americans and others of African descent.
By studying people of African ancestry who live outside that continent, scientists can see how similar genetic backgrounds play out in a variety of environments to promote or suppress diseases, said Charles Rotimi of the center.
Genes clearly aren't the whole story, because high blood pressure, diabetes and some other diseases are much more common in American blacks than in Africans despite the similar ancestry, Rotimi said.
Findings in American blacks will benefit everyone, said genome center director Georgia Dunston. About 80 percent of the black American DNA pool is rooted in Africa, which provides an unusually wide variation to begin with, Dunston said. Add to that the historical mixing-in of genes from people of European descent and American Indians, and you've got "a microcosm of human variation," she said.
Go, of the University of Alabama at Birmingham, said the results of that history of the black American gene pool should also make it easier to pinpoint schizophrenia-related genes.
Howard University's proposed "GRAD Biobank" -- GRAD stands for Genomic Research in the African Diaspora -- has not yet been funded beyond the planning stage. Participants would donate not only biological samples for DNA analysis, but also information on diet, lifestyle, access to health care, health beliefs and practices, and other factors considered environmental.
The Biobank proposal has some support among scientists, such as Dr. Esteban Gonzalez Burchard, who directs the DNA bank at the University of California, San Francisco.
"I think it's important, and I think we should do this in more populations," Burchard said.
But others have reservations. Troy Duster, a sociologist at New York University who studies social implications of biological research, said the Howard plan has the potential to be useful. But he's concerned that when genetic research is defined by racial groups, it seems to tell the public that race has more biological meaning than it actually does.
It's "giving a false reality to racial classification systems at a genetic level," Duster said.
What's more, no matter how often scientists say racial differences in disease rates come from complex interactions of genes and environment, he said, a race-based DNA approach tends to focus research and money on the genetic differences. And that could make policy-makers overlook non-genetic, potentially fixable factors, he said.
At Howard, Rotimi emphasizes that the genome center is looking beyond DNA for the causes of racial health differences. "A huge chunk of health disparities is the result of social experience," he said. "We don't relieve the society of its responsibility to make the necessary changes to begin to reduce the health disparity."
Duster also says he's concerned that race-based studies in general might go beyond diseases and unduly pin a genetic rap on blacks for crime.
Burchard, however, defends using racial classifications in biomedical research. If they were abandoned, he says, the search for potential genetic factors in racial health disparities would have to stop.
"At this point we don't know all the answers ... Let's not close the door yet," he said.
He acknowledges the risk that DNA data from biomedical research could be misused to fortify racism. But ignoring race brings the risk of passing up medical advances, he says.
And to him, "the risk of not looking under the hood ... far outweighs the risk of potential misuses."
