Friday, August 22, 2008

Genetic Variation Determines AIDS Risks in Blacks

Recently, new research discovers 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 have estimated that the trait, which also provides protection against a form of malaria, might account for 11 percent of the HIV cases in Africa, which is the continent that hardest hit by the AIDS epidemic.

Overall, the finding shows how the past history of evolution and disease still affects people nowadays, said study co-author Matthew J. Dolan, of the Wilford Hall United States Air Force Medical Center and San Antonio Military Medical Center. He added, "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."

Researchers have spent many years trying to understand why some people who are exposed to the AIDS virus are not infected. Interestingly, an estimated 70 percent to 90 percent of children born to infected mothers do not develop the disease, and some gay men have avoided it despite repeated exposure. Moreover, 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 researchers discovered that a genetic trait, which is found in 90 percent of Africans and 60 percent of African-Americans, makes HIV infection 40 percent more likely. The trait is virtually nonexistent in whites. In addition, the trait also protects people against a form of malaria that is now uncommon.

According to Dolan, it seems that the genetic makeup of some Africans have evolved to give them protection against the form of malaria. Moreover, he added, unfortunately, the trait ultimately, "set up the African continent for increased susceptibility" to HIV. Dolan has measured that the increased susceptibility could account for millions of extra cases of HIV.

On the other hand, according to Dr. Sunil K. Ahuja, a professor at the University of Texas Health Science Center in San Antonio, 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."

Rowena Johnston, vice president of research with the Foundation for AIDS Research, said the new finding provides even more evidence of an evolutionary struggle between humans and disease. Nevertheless, it will not be easy to make the information useful. She said, "Since any one individual has tens of thousands of genes, each of which may influence susceptibility in one direction or another, it's difficult to predict the outcome for any individual with any one particular genotype." Even if Africans or African-Americans discover they have this particular genetic trait, she asked, "What would they do with the information?" She added, as for using the new finding to develop a new anti-AIDS drug, which may be hard because of the limited effect of the genetic trait.

Read also:
South Africa to Ban Aids Vitamin Trials
U.S Plans for Large-Scale AIDS Vaccine

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