Genetic Trait Boosts AIDS Risks in Blacks

By Randy Dotinga
HealthDay Reporter
Wednesday, July 16, 2008; 5:00 PM

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WEDNESDAY, July 16 (HealthDay News) -- New research suggests that people of African descent are much more likely to have a genetic trait that makes them more susceptible to infection with the HIV virus.

Scientists estimate that the trait -- which also provides protection against a form of malaria -- might account for 11 percent of the HIV cases in Africa, the continent hardest hit by the AIDS epidemic.

Overall, the finding shows how the past history of evolution and disease still affects people today, said study co-author Matthew J. Dolan, of the Wilford Hall United States Air Force Medical Center and San Antonio Military Medical Center. "The benefit that the Africans got from a mutation that gave them some resistance to malaria has, statistically at least, rendered them some increased susceptibility to HIV," he said.

Researchers have spent years trying to understand why some people who are exposed to the AIDS virus don't get infected. An estimated 70 percent to 90 percent of children born to infected mothers don't develop the disease, and some gay men have avoided it despite repeated exposure.

In the new study, a team of researchers studied more than 1,200 members of the U.S. military who became infected with HIV. They wanted to discover more about how genetics affects the disease.

The findings were published in the July 17 issue of Cell Host & Microbe.

The researchers found that a genetic trait -- found in 60 percent of African-Americans and 90 percent of Africans -- makes HIV infection 40 percent more likely. The trait is virtually nonexistent in whites.

The trait also protects people against a form of malaria that is now uncommon.

It appears that the genetic makeup of some Africans evolved to give them protection against the form of malaria, Dolan said. Unfortunately, the trait ultimately "set up the African continent for increased susceptibility" to HIV, he said.

Dolan estimated that the increased susceptibility could account for millions of extra cases of HIV.

On the other hand, people who have the trait live an average of two years longer with the disease once they get it, the researchers found. "It's a two-edged sword," said study co-author Dr. Sunil K. Ahuja, a professor at the University of Texas Health Science Center in San Antonio.