Epidemiological studies conducted on samples from longitudinally followed PLWH enrolled in the Multicenter AIDS Cohort Study found an association between certain KIR3DL1/HLA and KIR3DS1/HLA combinations with time to the acquired immunodeficiency syndrome (AIDS) (using the 1987 US Centers for Disease Control and Prevention’s definition for AIDS), time to CD4 counts of <200 cells/mm3 and HIV viral load control [67,68]. The gene discussed is CD4; the disease is AIDS.