But in cases where a CD4 assay is available, ART will be started for WHO stage IV disease (when PLHIV develop AIDS) regardless of CD4 count, or WHO stage III disease (presence of symptoms due to opportunistic infections) with CD4 count below 350 cells/mm3, or asymptomatic disease with CD4 count below 200 cells/mm3 [14]. The gene discussed is CD4; the disease is Opportunistic infection.