South African guidelines include baseline CD4 testing for ART patients to assess cotrimoxazole prophylaxis (CPT) eligibility (where CD4 count is ≤ 200 cells/mm3) and to determine susceptibility to opportunistic infections.8 CD4 monitoring should be repeated 12 months after ART initiation, 6 monthly until CPT eligibility ceases, 6 monthly if VL increases above 1000 copies/mL and if a patient requires re-initiation onto ART.8 Such CD4 testing is critical to ensure correct ACC management for patients with low CD4 counts to mitigate higher morbidity and mortality risks. The gene discussed is CD4; the disease is Opportunistic infection.