FEW topics are as contentious as race. The idea and its history, from eugenics onwards, are tainted, and whenever it knocks up against science problems quickly surface. So expect fierce debate in coming weeks as the US Food and Drug Administration considers whether to license a heart drug, BiDil, for black people only.
On the face of it, a drug that has been shown to benefit people who do not respond well to existing front-line drugs is a cause for celebration. But BiDil has reignited old disputes about whether race has any scientific validity and what role it should have in medical decision-making.
It was European naturalists in Victorian times who popularised the notion of race. But trouble set in as soon as the concept was subjected to systematic study, and all attempts to unambiguously assign individuals to one race or another according to their physical characteristics have failed. Attempts to use genetics initially fared no better. Looking at single genes, researchers found more variety within racial groups than between them.
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In recent years, researchers have had more success in allocating Americans to broad racial groups by looking at hundreds of genetic markers. This is hardly surprising. For most of their history, human populations have been geographically isolated, so genes tended to cluster with geography, and our notions of race have similar geographical roots. African Americans, for instance, come mostly from one geographical area: west Africa.
But this does not mean that other racial categories are meaningful. Black Britons, for example, have ancestors not only from west Africa, but from southern and east Africa too. People in this group are unlikely to be genetically uniform. Added to this, the geographical separation of human populations is rarely perfect, so some people will inevitably find themselves in the wrong group. Others will find no home at all.
Even if a person鈥檚 race is beyond doubt, this does not usually say much about how they will react to particular drugs. That is because racial groupings have been shown to correlate poorly with genes that code for the enzymes that metabolise drugs. Taking all these factors into account, race will usually be an unreliable way of targeting people for a particular medical treatment. There is an argument that geographical ancestry is a more useful tool. For example, Americans of Puerto Rican ancestry suffer more asthma than those who hail from Mexico and do not respond as well to anti-asthma drugs. Both groups are classified as Hispanics, but by asking which country their ancestors came from, some differences between them become clearer.
Despite this, for BiDil, race seems to be the best indicator of the drug鈥檚 likely usefulness. One intriguing possibility is that BiDil鈥檚 success with African Americans has nothing to do with genes and everything to do with environment. Much has been made in the past few years of status anxiety 鈥� the idea that stress is worst among those at the bottom of the pecking order. Stress, we know, damages people鈥檚 health, and in particular induces oxidative damage in the body. One of BiDil鈥檚 components is an antioxidant. Could it be that BiDil鈥檚 success is telling us more about African Americans鈥� place in society than about their genes? Such an outcome would not invalidate using race as a test of whether BiDil should be given. But it does suggest that we do not know what it is testing 鈥� and we need to find out.
鈥淩ace will usually be an unreliable way of targeting people for a particular medical treatment鈥�
If it is genetic differences that count with BiDil, then race could be merely a surrogate for a gene or genes that cause some people to have lower levels of nitric oxide in their blood vessels and hence predispose them to heart failure. Ideally, we would be able to identify those genes so that those in danger can be given the drugs. Also, this would single out the African Americans unlikely to benefit from BiDil, and the few people from other races who would benefit.
Pharmacogenomics, the idea of tailoring drugs to the individual, holds great promise but is yet to yield real benefits. Perhaps it is time to launch a publicly funded Human Pharmacogenomics Project or to require companies that win licences for 鈥渞ace-based鈥� drugs to spend a proportion of their revenue on identifying the genes in question. Until we understand the influence of genes, notions of race will continue to haunt science, and contention will continue to reign.
