The step-wise backward selection process to identify the most relevant predictors of outcome (retaining the variables with a p-value of ≤0.15) identified sputum smear grade [or sputum smear status (positive or negative)], previous history of ATT, disease classification (pulmonary versus extra-pulmonary), HIV and ART status at the time of TB diagnosis, and CD4 cell count at the time of initiating the patient on ATT as the most important predictors for unfavourable outcome. The gene discussed is CD4; the disease is tuberculosis.