A genetic variation that protects people of African descent against a particular form of malaria may also be responsible for making them up to 40 percent more susceptible to HIV, the virus that causes AIDS, according to a new study, reports The Wall St. Journal.  

When exposed to the virus, "most Africans have a slight genetic bias to being more susceptible," says Robin Weiss, a virologist at University College London, who co-wrote the study for a new scientific journal, Cell Host & Microbe. Africa has 25 million people with the virus, a much higher rate than other populations.

The researchers also found that the same ancient "genetic alteration" appears to prolong survival in those with the HIV virus by approximately two years, according to the Journal. "It helps in part to explain why HIV is so prevalent in Africa," Weiss said.

Researchers are hopeful that understanding more about the genetic roots of HIV will assist in the creation of additional vaccine trials. According to the study, 90 percent of people in Africa and 60 percent of African Americans carry the variant gene. The scientists estimate that this variant gene may be responsible for some 11 percent of the HIV burden in Africa.