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Race Complicates Views on Genes And Medicine
Physicians have known for millennia that heredity affects health, and the post-genome era has dramatically increased what is known about connections between genes and disease. This knowledge explosion has spawned new diagnostic tests, rationally designed treatments, and sometimes new preventive strategies. It is too well accepted to spark even a lively dinner conversation.
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David Altshuler says that the main purpose of searching for genetic risk factors is to uncover the mechanisms of disease, not to individualize therapy. |
Insert the word race into the discussion, however, and you draw a crowd. More than 120 people ignored a gloriously sunny Saturday to participate in “Race, Genetics, and Medicine: New Information, Enduring Questions,” a conference organized by the Genetic Study Screening Group and held at the Harvard University Science Center on April 9. Experts in genetics, sociology, anthropology, clinical medicine, law, and the history of science examined the scientific and political risks—and perhaps benefits—of bringing the concept of race into the laboratory or clinic. The roster featured two Harvard faculty members: physician-scientist David Altshuler and science historian Evelynn Hammonds.
The Biology
of Race
“Big Science” undertakings such as the Human Genome Project sometimes
generate spin-offs that dwarf their original mission, said keynote speaker
Troy Duster. Witness how the World Wide Web completely overshadows the
high-speed military communications network that gave rise to it.
In the early 1990s, the Human Genome Diversity Project (HGDP) collected blood samples from 52 populations and created more than 1,000 immortalized cell lines, since used by experimenters around the world. Numerous studies show that people from different continents and regions have distinctive haplotype maps, “and the spin on these findings is that race is not a social construct, and as a result, race is being re-inscribed in biology, said Duster, author of Backdoor to Eugenics and a sociology professor at New York University and the University of California, Berkeley.
Although the term race may have a place in descriptive social science research, Stanford University geneticist Marcus Feldman prefers to talk about “ancestry.” In a landmark report published in Science in 2002, Feldman described using 377 single nucleotide polymorphisms (SNPs) to analyze sequence data for 1,060 HGDP samples stripped of all racial, ethnic, or geographic identifiers. These markers sorted the samples into five clusters, and when the code was broken, these groupings corresponded to populations now found in Africa, Europe, North America, and two regions of Asia. These clusters reflect ancient land migrations from Africa that predate long-distance sailing, said Feldman, a professor of biology at Stanford.
Asked if his findings were useful for clinical medicine, Feldman was dubious. “No marker perfectly specifies any group. Most people have multiple ancestries, and we can infer ancestry from genotype, but we can not infer genotype from ancestry,” he said.
| “No marker perfectly specifies any group. Most people have multiple ancestries, and we can infer ancestry from genotype, but we can not infer genotype from ancestry.” |
Burchard’s clinical practice focuses on Latino children with asthma, and he and his colleagues recently used spirometry to compare how children of Mexican or Puerto Rican ancestry respond to albuterol, the most common pediatric asthma therapy. They found that Puerto Rican children were least likely to attain the 12 percent increase in lung function that defines successful albuterol treatment, while Mexican children got much better results.
“We see significant racial disparities in disease and drug response, and while I readily concede that much of that has to do with socioeconomic status, access to care, and discrimination, I would never advocate blowing off the possibility that biological differences may help explain some of what we see clinically,” Burchard concluded.
A Race-based Therapy
The highest profile example of “race-based medicine,” cited
repeatedly during the conference, is the FDA’s recent approval
of BiDil (a combination of isosorbide dinitrate and hydralazine) as
a hypertension
treatment for African-American patients. While University of North
Carolina anthropology professor Jonathan Marks hopes that someday doctors
will be
able to match treatment with an individual’s genotype, right
now the mixed heritage of most Americans makes skin color a dangerous
basis
for writing prescriptions. “Race-based medicine would probably
kill more people than it would cure,” he said.
Individualizing medical treatment is not the point, objected Altshuler, HMS associate professor of genetics at Massachusetts General Hospital and a director of medical and population genetics at the Broad Institute. “The main purpose of searching for genetic risk factors is we have no idea what causes most diseases,” he said, and experience shows that great benefits result when a genetic cause can be identified. Although familiar hypercholesterolemia is a rare disease, finding the gene for it led to the discovery of a cellular pathway that, in turn, led to the development of statins—drugs now preventing and treating coronary heart disease in millions of people.
Speaking on the day’s last panel, Altshuler and Harvard historian Hammonds agreed that the media confuse the public by sensationalizing news about genetics, race, and medicine. “Controversy sells newspapers,” Altshuler said.
The media also pick up on “straw men” created by biologists and social scientists who misrepresent one another’s positions to enliven the debate, said Hammonds, a professor of the history of science and of African and African-American studies at Harvard University. This is problematic in an era when “many media outlets serve as mouthpieces for political agendas,” she said. The history of race in America shows that powerful people have often been receptive to what she calls “biological explanations for social problems,” especially if these can be used to argue that nothing needs to be done to improve schools, prisons, or health care.