CCR2 and AIDS: CCR2-64I mutation, involving a valine-to-isoleucine substitution at position 64 of the CCR2 receptor, does not appear to affect initial susceptibility to HIV infection, individuals who are heterozygous (wt/mt) or homozygous (mt/mt) for this mutation tend to experience slower disease progression possibly due to delayed viral replication, with delayed onset of AIDS or prolonged survival [10].