Earlier studies have revealed the central role of IL-2 and IFNγ as survival and proliferative factors (70, 71) in HIV-1 infection; as disease progresses, the frequency of IL-2-producing CD4+ T-cells is found to decline (42), which in turn relates to the reduced renewal capacity and increased susceptibility of these populations of cells to apoptosis (70). The gene discussed is IFNG; the disease is HIV-1 infection.