Genetic HIV Resistance Deciphered

hexed_2050 writes "Researchers have pin-pointed the reason why some people have a greater immunity, or in some cases, total immunity to the HIV virus. They credit a genetic defect that can be traced back to Europeans in the middle ages."

Comments

Future evolution

[Lonesome Squash]

The number of people who die from AIDS is a very strong selection pressure. Unless the epidemic is halted medically, we can expect that it won't be many generations before these mutations are nearly universal. If they have lingered this long in the population, they can't be strongly deleterious.

Eventually we will probably be like the chimpanzees, who have a pronounced lack of diversity in the genes for certain immune receptors as well as immunity to AIDS. Scientists view this as evidence that an AIDS-like plague swept through the Chimpanzee population in the not-too-distant past.

The idea that AIDS will one day burn itself out of the population may not be much comfort to those who have it, nor to those who must grow up in a world where they must face that risk -- especially for those growing up in coutries with 40% infection rates. But I find it comforting, anyway.

I did say "nearly universal"

[Lonesome Squash]

This is a recessive mutation (ignoring partial immunity for a minute). The truly-immune percentage of the population will be the square of the gene frequency. Let's say that AIDS begins to recede when 36% of the population is immune. For 36% of the population to be immune, 60% of the genes will need to be the mutated variety. At that point only 16% of the population will be carrying two non-mutated genes. Okay, maybe I exaggerated the "not many generations" but the point stands.

This is the opposite of the recessive extinction problem, where the percentages work against you (that's why deleterious recessives thrive so well when they are rare).