A gene extremely common among Africans but almost unknown other ethnic groups may be rendering people of sub-Saharan Africa more susceptible to HIV and AIDS, the Times of London reports. The gene variant—common because it provides malaria protection—makes carriers 40% more likely to contract HIV and could be responsible for 11%, or 2.5 million, of the AIDS cases in Africa, the continent hardest hit by the disease.
“After thousands of years of adaptation, this variant rose to high frequency because it helped protect against malaria," said an expert at the San Antonio Military Medical Center. "Now, with another global pandemic on the scene, this same variant renders people more susceptible to HIV. It shows the complex interplay between historically important diseases and susceptibility." (Read more HIV stories.)