One copy of mutation may help resistance: study.
It's well-known that the homozygous type of two copies of the 32 base pair deletion in the CCR5 chemokine receptor provides resistance to HIV-1 infection. But there have been fewer data pertaining to what happens when a person has only one copy of the CCR5 delta 32 genotype. A recent study shows that even heterozygous CCR5 32 genotype, found primarily in European Caucasians, provides significant protection from infection during exposure to HIV-1.