The levels generated by Liu et al [30] showed a best performance of this biological marker when compared to ADA to differentiate TB from malignant pleural effusions (IFN-γ: Cut-off = 70 pg/mL, AUC = 0.960, Se = 91.7%, Sp = 97.6%, PPV = 95.7%, NPV = 95.3%; ADA: Cut-off = 30 IU/L, AUC = 0.760, Se = 70.8%, Sp = 95.2%, PPV = 89.5%, NPV = 85.1%). The gene discussed is ADA; the disease is tuberculosis.