After adjusting for these variables, there continued to be a significant effect of VACS Index (χ2 = 28.56, p < 0.001, OR = 1.07, CI = 1.04–1.09) on the domain of Attention but there was no association between nadir CD4 cell count (p = 0.87), time since HIV diagnosis (p = 0.82), diagnosis of AIDS (p = 0.76), ART status (p = 0.20), duration of ART (p = 0.60) and Efavirenz-based ART regimes (p = 0.99) with this respective domain. The gene discussed is CD4; the disease is AIDS.