CCR5 and HIV-1 infection: Dean et al.,11 examined the progress of HIV to AIDS in the US population with different levels of exposure to HIV ranging from intravenous drug users, persons with hemophilia, and homosexuals, they observed that the heterozygous individuals of CCR5-Δ32 had a two year delay in the progression to AIDS when compared with the homozygous wild type.11 This shows that heterozygous CCR5-Δ32 (CCR5-wt/ CCR5-Δ32) are not immune from HIV-1 infection but have a slow progression to AIDS.