A variety of studies conducted in the 1990s examined the associations between C-C chemokine receptor 5 (CCR5) polymorphisms (a 32-base pair deletion [Δ32, rs333] in the open reading frame [ORF] and a single nucleotide polymorphism [SNP] −2459G > A [also known as 59029G > A and 303G > A, rs1799987] in the promoter) and HIV-1 infection and disease progression. The gene discussed is CCR5; the disease is HIV-1 infection.