Dating the origin of the ccr5 delta32
It is hypothesized that the imbalanced distribution of this allele was caused by environmental selective pressure, resulting in positive selection for the delta32 deletion .
CCR5 has gained prominence as a cofactor for HIV-1 entry.
Hence, 74 mutations have been described in this gene up to date including the intensively studied 32 base pair deletion (CCR5-delta32) that introduces a premature stop-codon into the CCR5 locus [5–7].
Epidemiologic studies have shown that the mutation occurs most frequently in the Caucasian population with up to 10-20% heterozygous and 1% homozygous carriers, while it can not be found in the Asian, Middle East, African, and the American Indian population .
Apart from the role in HIV infection, the CCR5-delta32 mutation seems to be a modulator regarding immune responses and transplantation immunology.
There has also been proposed an association of the mutation with the occurrence of allograft rejection and protection against graft-versus-host disease (GVHD) [18, 19].