CCL3L1 (chemokine (C-C motif) ligand 3-like 1)
CCL3L1, or Chemokine (C-C motif) ligand 3-like 1, has copy number variation in human populations, and this variation is known to affect resistance to HIV, causative virus for AIDS. Because AIDS was introduced to modern human very recently (within 200 years), initial function of CCL3L1 is obviously not for HIV resistance.
Copy number variation (CNV) between 1-6 copies exists.
CCL3L1 copy number is a strong genetic determinant of HIV seropositivity in Caucasian intravenous drug users., , J Infect Dis, 2010 Mar, Volume 201, Issue 5, p.730-9, (2010)
CCL3L1-CCR5 genotype influences durability of immune recovery during antiretroviral therapy of HIV-1–infected individuals, , Nature medicine, 04/2008, Volume 14, Issue 4, p.413-20, (2008)