Discriminating Medicine
Using race and ethnicity to improve medical care
Earlier this year, the FDA approved BiDil as a drug for the treatment of heart failure in self-identified black patients. Since politically correct dogma holds that there are no relevant genetic differences between races, many opposed BiDil as ipso facto racist.
BiDil works by increasing the level of nitric oxide in the body, which in turn relaxes the smooth muscle cells that line arteries. This widens arteries enabling the heart to pump more blood with less pressure. BiDil is effective for black patients suffering from heart failure because blacks tend to have lower average amounts nitric oxide. Scientists believe that this lower level of nitric oxide could be an evolutionary adaptation that helped their African ancestors retain scarce salt in tropical climates. Whatever the reason, black patients taking BiDil had a 43 percent reduction in death and a 39 percent decrease in hospitalization for heart failure.
Last week, geneticist Kari Stefansson, the founder of deCODE genetics, announced that his company had found a version of a gene that raises the risk of heart attack in African-Americans by more than 250 percent. The same gene variant increases the risk of heart attack in whites and Asians by 16 percent. The gene is a more active variant of the LTA4H gene which boosts inflammation as a way to fight infections. This version apparently arose in whites and Asians sometime after their ancestors had departed Africa and is not generally found in sub-Saharan populations. However, inflammation is known to increase the risk of heart disease. Stefansson speculates that white and Asian carriers of this more active gene variant experience relatively less risk of heart attack because other of their genes have evolved to counterbalance it. This more active gene was introduced into contemporary African-American populations just a few generations ago, and their genomes have not had time to adjust to it.
According to deCODE, 30 percent of white Americans bear the active version of the gene, while 6 percent of contemporary African-Americans have inherited it. "If you're an African American with the variant gene you are close to certain to have a heart attack if nothing is done about it," said Stefansson in New Scientist. "It's very important to screen and find this subgroup."
deCODE is currently developing a new drug, DG031, that inhibits the molecular inflammation pathway that incorporates the LTA4H gene. The company is also creating a diagnostic test that physicians could use to detect the gene. BiDil is broadly used to treat members of a racially defined population who suffer from heart failure. If it turns out that DG031 is effective, physicians would use race as a criterion for testing and prescribe the drug only if an individual black patient carries the active version of the gene.
Unfortunately, the resistance to race-based medicine is grounded in a history of abuse. Consider the case of sickle cell anemia, a genetic disease in which red blood cells may deform into a distinctive crescent shape under certain circumstances. These crescent shaped cells get trapped in capillaries, causing downstream tissues to be deprived of oxygen, which causes debilitating pain. Sickle cell anemia is a recessive genetic disease, so a person must inherit two copies of the gene in order to get it. Biologists believe that the African ancestors of American blacks who carried one sickle cell gene and one normal blood cell gene had a genetic advantage, because they were more resistant to malaria.
In the 1960s and early 1970s, several states enacted mandatory sickle cell anemia testing for all newborn blacks. People who tested positive as carriers of a single copy of gene often experienced discrimination in employment and in obtaining insurance. Keep in mind that such carriers do not have the disease and are as healthy as anyone else. Nevertheless, the U.S. Air Force once restricted healthy personnel from flying if they were sickle cell carriers.
Devising new medical tests and treatments based on membership in specific ethnic groups is not confined to blacks. One in 800 people carry the mutation of BRCA 1 gene which predisposes them to breast cancer. However, one in 40 women of Ashkenazi Jewish descent carry certain specific mutations in the BRCA 1 and BRCA 2 gene that increase their lifetime risk of breast cancer to as much as 80 percent. (That is, 8 out of 10 women who carry these mutations will get breast cancer at some point in their lives.) Now there is a test for these gene variants which can alert women who might consider prophylactic mastectomy as a way to reduce their risk of breast cancer.
The sorry history of race-based medicine should not be allowed to block the development of treatments that will be increasingly tailored to each patient's genetic makeup. One day we'll each have our whole genomes scanned for gene variants that put us at risk for a whole range of diseases. Until then, it would be wrong not to use the clues—including those linked to race and ethnicity—that researchers and physicians have now to guide them in providing the best possible medical care for their patients. In cases of BiDil and DG031, if race had not been used as a criterion for testing, neither drug would have been discovered, and black patients would not now have access to these beneficial medicines. That really would have been invidious racial discrimination.
Ronald Bailey is Reason's science correspondent. His book Liberation Biology: The Scientific and Moral Case for the Biotech Revolution is now available from Prometheus Books.
