March 2005

Synopses: Biotechnology

Genes put African Americans at higher risk of disease; fat secretes hormone that may control diabetes; toward a plausible RNAi therapy.

By Monya Baker (edit)

Inflammatory Genes
Genes may put African Americans at higher risk of disease

CONTEXT: Heart disease, stroke, transplant rejection, and autoimmune diseases kill African Americans at a higher rate than white Americans. Access to health care, health behaviors, and socioeconomic and community factors explain many, but not all, of these disparities. Genetic differences are often discounted, because variations within a single racial group are larger than variations among racial groups and because race is increasingly viewed as a social construct rather than a biological one. Nonetheless, race-based medicine is hotly debated, and race-specific therapies are being studied. Many diseases that disproportionately afflict African Americans are linked to inflammation or an overactive immune system. To test whether genetics plays a role in these diseases, Roberta Ness and colleagues at the University of Pittsburgh tracked nearly 600 women to examine genetic variants known to promote inflammation.

METHODS AND RESULTS: The researchers tested for variants of six different genes among healthy women who received prenatal care before successful first births. Of these, 179 identified themselves as black, 387 as white. The genes coded for proteins, called cytokines, that regulate the immune system. For five of the six genes studied, black women were more likely than their white counterparts to carry a proinflammatory variant; the difference was statistically significant for four genes. For one gene, black subjects were 36.5 times more likely than whites to carry two copies of the proinflammatory variant. However, for any single gene, many white women carried a proinflammatory variant, and many black women did not.

WHY IT MATTERS: Improving unhealthy living conditions and habits and reducing social disparities will be most effective in preventing inflammatory disease; still, tests that show who is most likely to fall ill could help those at risk get preventive counseling and care. By demonstrating a genetic contribution to disease that is race-specific, this work suggests that race could be used as a shorthand for genetic predisposition to guide medical advice. This notion is controversial because of the high genetic variation within racial groups. Making decisions based on race alone will include some people who can't benefit from treatment and exclude others who can. To resolve this issue, genetic tests to assess risk factors should be developed. Meanwhile, using race as a kind of genetic proxy to inform preventive care might deliver the most good to the most people.

SOURCE: Ness, R. B., et al. 2004. Differential distribution of allelic variants in cytokine genes among African Americans and white Americans. American Journal of Epidemiology 160:1033-1038.