However, treatment failure (defined either as clinical failure—AIDS-defining event; virologic failure—having two consecutive viral loads > 1000 copies/mL with adherence counseling between measurements (a WHO standard commonly used in Low and medium-income countries (LMIC) in SSA); or immunologic failure—CD4+ cell count < 200 mm3) is regarded by most experts as the most formidable problem. The gene discussed is CD4; the disease is AIDS.