Evidence: Race & DNA

LAW 6330 (4 credits)
Professor Pedro A. Malavet
Fall 2012
Mondays and Wednesdays
3:00-4:50 p.m.
Room 285B

NOTE: This article from the New York Times, discusses the debate over the significance and validity of using racial categories in DNA testing.

--Prof. Malavet

Posted: Monday, April 7, 2003

The New York Times

March 20, 2003, Thursday, Late Edition - Final

Section A; Page 30; Column 5; National Desk

2 Scholarly Articles Diverge On Role of Race in Medicine

By NICHOLAS WADE

Responding to recent advances in decoding DNA that have thrown light into a murky corner of genetics, two articles in The New England Journal of Medicine today take different views on whether race is a meaningful factor in medicine.

In addition, a staff-written commentary suggests that the journal's own view on the subject may have softened in the two years since it ran an editorial attacking "the fallacy of race as a scientific concept."

The issue of race and medicine arises because certain diseases are more common in some ethnic groups than others. One well-known instance is sickle cell anemia, most prevalent in Africans, and another is Tay-Sachs, more common among Jews.

A view widespread among many social scientists, endorsed in official statements by the American Sociological Association and the American Anthropological Association, is that race is not a valid biological concept. But biologists, particularly the population geneticists who study genetic variation, have found that there is a structure in the human population. The structure is a family tree showing separate branches for Africans, Caucasians (Europe, the Middle East and the Indian subcontinent), East Asians, Pacific Islanders and American Indians.

Biologists, too, have often been reluctant to use the term "race." But this taboo was broken last year by Dr. Neil Risch, a leading population geneticist at Stanford University.

Vexed by an editorial in The New England Journal that declared that race was "biologically meaningless," Dr. Risch argued in the electronic journal Genome Biology that self-identified race was useful in understanding ethnic differences in disease and in the response to drugs.

Race corresponded broadly to continental ancestry and hence to the branches on the human family tree described by geneticists, he said.

Expanding this argument today, Dr. Risch and nine co-authors say that ignoring race will "retard progress in biomedical research."

Racial differences have arisen, they say, because after the ancestral human population in Africa spread throughout the world 40,000 years ago, geographical barriers prevented interbreeding. On each continent, under the influence of natural selection and the random change between generations known as genetic drift, people would have diverged away from the common ancestral population, creating the major races. Within each race, religious, cultural and geographical barriers fostered other endogamous, or inbreeding, populations that led to the ethnic groups.

These divisions in the human population, though very slight in comparison with the genetic variation inherited in common from the ancestral population, can be important in understanding many diseases, Dr. Risch says. Many rare diseases are often specific to single ethnic groups because of a founder effect: They were present in the founder and became more noticeable as the group, while remaining endogamous, grew in number. Many such diseases are known among such well-studied groups as Ashkenazi Jews, French Canadians and the Amish.

Common diseases are found worldwide. But though much less is known about them, they may be caused by different genes in different racial groups, Dr. Risch says. In Caucasians, mutations in a gene called CARD15 make a person susceptible to Crohn's disease, but Japanese with Crohn's disease have none of these mutations. Presumably a different gene, yet to be found, contributes to Crohn's in Japanese.

"It may be tempting to abandon the notion of race altogether," Dr. Risch and his colleagues write, especially if attention to racial differences should perpetuate discrepancies, but because of the leading clues provided by race to the cause and treatment of disease, such a course "would be detrimental to the very populations and persons that this approach allegedly seeks to protect."

An opposing article by Dr. Richard S. Cooper, of the Loyola Stritch School of Medicine in Maywood, Ill., is more skeptical. Doctors have been too quick, Dr. Cooper and his co-authors write, to suggest genetics as the reason for the greater susceptibility of African-Americans to certain diseases, when the true reason may be social factors.

Dr. Cooper, an expert in the epidemiology of heart disease, agrees that some rare diseases are particular to certain populations, but he says the genetic variants that underlie common diseases are not.

"We can expect genomics increasingly to negate the old-fashioned concept that differences in genetic susceptibilities to common diseases are racially distributed," he says. For example APOE4, a genetic variant that contributes to Alzheimer's disease, is found in all populations, he writes.

But even with APOE4, Dr. Risch says, knowledge of racial background provides important insights because the risk conferred by the gene varies by race. Inheriting two APOE4 genes, one from each parent, raises the risk of Alzheimer's 33 times in Japanese populations, 15 times in Caucasians and only 6 times in Africans. This suggests that some unknown factor modifies the effect of the APOE4 gene in different races, he says.

Dr. Cooper is also concerned that if medical geneticists were to prove that race is a valid biological concept, then social and political aspects of race, some not so benign, might also seem to be validated.

"Race already has a meaning," he writes. "To invoke the authority of genomic science in the debate over the value of race as a category of nature is to accept the social meaning as well."

Two years ago an editorial by Robert S. Schwartz, deputy editor of The New England Journal, dismissed the idea of race as a scientific concept. But in today's issue another deputy editor, Elizabeth G. Phimister, says only that it "remains to be seen" whether continental-based racial definitions will help track the variant genes that cause common diseases.

Dr. Phimister concludes that it would be "unwise to abandon the practice of recording race when we have barely begun to understand the architecture of the human genome" and its clues to the genetic basis of disease.

She said in an e-mail message, however, that an editorial in the journal "conveys the views of the author only, rather than views germane to journal policy."

Dr. Risch said in an interview that anxiety about the genome and race might have arisen among minorities who did not always feel in control of their own genetic information. Despite initial fears of discrimination, he said, Jews had taken charge of the information about diseases more common in Ashkenazis and now accepted its usefulness.

"The more minorities we can get doing the research, the more these issues will dissipate," he said.

http://www.nytimes.com