Saturday, March 22, 2008

Genetics' Role in Health Disparities

Charles Rotimi explains why a more complete snapshot of genetic variation is important.

Race and medicine: Charles Rotimi, a genetic epidemiologist, will head a new center at the National Institutes of Health to research diseases disproportionately affecting minority groups.
Credit: NHGRI

The last year has seen an explosion in studies linking specific genetic variations to common illnesses, such as diabetes and heart disease. But how common are these variations in different groups, and do they play the same role in different populations? Those are just two of the questions that genetic epidemiologist Charles Rotimi aims to answer as head of a new center devoted to the study of genetics, lifestyle, and disease in minority groups, at the National Institutes of Health, in Bethesda, MD.

Rotimi's research has focused on obesity, hypertension, and diabetes--three disorders that disproportionately affect African Americans; together, the high rates for these diseases account for more than 80 percent of the health disparities between African Americans and European Americans. The new Intramural Center for Genomics and Health Disparities will attempt to uncover the reasons for the differences by exploring the interactions between genetics and environment in African and African-American populations. While many disparities are clearly linked to socioeconomic factors and a lack of access to medical care, genetics may also play a vital role. A genetic vulnerability to hypertension or diabetes, for example, may only be realized in an environment with easy access to high-salt, high-fat foods. Genetic variations can also impact how well a drug works, or whether it will induce harmful side effects in the patient taking it. The variations can occur at different frequencies in different populations--something that needs to be taken into account when studying and prescribing new medicines.

Technology Review recently asked Rotimi to explain his work and its importance.

Technology Review: Why was the center created?

Charles Rotimi: We are right at the point where genomics is beginning to yield interesting fruits, and we want to see those fruits shared by all populations across the world.We want to take advantage of the fact that we are making considerable progress in understanding genetic variation and how it impacts the disease distribution we see across different populations. Only by including all populations can we truly understand human genetic variation and its importance for disease and response to drugs.

The center is set up to take advantage of all of these genomic tools, as well as to try to understand things like culture and lifestyle, and how they interact with genetics in terms of human disease. We want to look specifically at diseases that disproportionately affect minority groups in the United States, including obesity, hypertension, and diabetes.

We are trying to advance research into the role of culture, lifestyle, and genomics--not just genes, but the interactions between genes and environment--to help us understand common complex diseases. Because Africa is the original source of all human migration, whatever we find will be informative for the general population, not just the African people.

TR: Do you think the general public has a misconception about genetics and race?

CR: Yes. The misconception is that genetics can be used to unequivocally identify all members of a particular "race," compared to others. While it is true that, with enough genetic markers, it is possible to draw imprecise boundaries such as "Africans," "Europeans," and "Asians," there is no set of genetic markers that can be used to identify all persons that self-identify as belonging to a "racial" group without error.

Despite this, scientists have been unable to move beyond racial categorization in science, medicine, and society. Partially responsible for our continued obsession with race is the fact that, although we do not have distinct biological types of "races," we do have differences in the frequencies of genetic markers across human ancestral groups. These differences, which for the most part describe geographically distant populations, are believed to harbor the answers to why some individuals and groups may be more susceptible or resistant to diseases, and may also hold the key to understanding why certain groups respond differently to medications.

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