HIV-1/AIDS susceptibility and copy number variation in CCL3L1, a gene encoding a natural ligand for HIV-1 co-receptor CCR5

Variations of gene copy number in the human genome are increasingly recognized as a genetic factor in phenotypic variation. Human CC chemokine ligand 3-like 1 gene (CCL3L1), which is located on human chromosome 17q11.2, is highly variable in copy number owing to having a hot spot for segmental duplications. CCL3L1, a natural ligand for HIV-1 co-receptor CCR5, is a potent HIV-1-suppressive chemokine. CCL3L1 copy number variation (CNV) is tightly linked to HIV-1/AIDS susceptibility, and a lower copy number is associated with an enhanced risk for acquiring HIV-1 and also progressing more rapidly to AIDS and death. In this article we review recent studies to evaluate the association between the CCL3L1 copy number and HIV-1/AIDS susceptibility.