CXCL12 and HIV-1 infection: The present study shows an association between the 3′A allele variant and the decline in CD4+ TL, probably due to an increased expression of SDF1 mRNA during the more advanced stages of HIV-1 infection, but the presence of the CCR5∆32 and SDF1-3′A gene variants were not associated with a better response against viral multiplication or control by the host.