Medical Response Not All Black and White
Study authors and other experts are unanimous that the explanation lies in genetic differences -- still to be unveiled -- in the way individual patients process individual drugs. In the era of the Human Genome Project, skin color will disappear entirely as an explanation for why people respond to differently to treatment, argues Robert S. Schwartz, MD, an NEJM editor .
"The publication of the first draft of the sequence of the human genome should force an end to medical research that is arbitrarily based on race," Schwartz writes in an accompanying editorial. "The Human Genome Project now gives us the power to uncover the true origins of genetic variations; linking them to race has become passe."
Yet until science has determined the specific genetic variations that cause one individual to respond differently to a drug than another, researchers are left with studying populations according to the only readily apparent distinguishing factor -- skin color.
Cohn, for instance, acknowledges that the difference in response to Vasotec may have nothing to do with skin color, but instead with fine variations in genetics between individuals. In the study, "the only distinguishing feature is their skin color," Cohn says. "But we recognize that there will be many responders among African-Americans, and many nonresponders among whites."
And he agrees that the human genome project will take researchers beyond skin color in understanding differences in treatment response. Soon, the science of tailoring drugs to specific genetic differences will dissolve the apparent differences between blacks and whites until they are seen for what they are: variations among individual people.
"We are entering a new era," he tells WebMD. "Although there may be great reluctance to take these studies on, the time has come to explore these things."
"When we see racial or ethic differences in response to a drug, that may be a clue that there is an underlying genetic difference and may point us in a direction to look for those differences," Alastair Wood, MD, tells WebMD. Wood, who is vice chancellor and professor of medicine at Vanderbilt University School of Medicine, in Nashville, wrote a second editorial accompanying the reports.
Wood says refinement of genetic research will likely show that the genetic differences affecting response to treatment are not specific to one race or another, but occur randomly across races. Some races and ethnic groups may be more likely to carry the genetic variation, but not all members of that group will carry it.
He likens it to fitting a suit for an entire population: A suit tailored to fit a population of American men would be unlikely to fit many typically smaller Chinese men -- but it may well fit some, and would be just as unlikely to fit some Americans.