Meanwhile, 42 patients (21.0%) had invalid results of QFT-GIT assay due to higher IFN-γ concentrations (> 8 IU/mL) in the Nil control tube (1 patient) or lower IFN-γ concentrations (< 0.5 IU/mL) in the positive control tube (41 patients), including 31 TB patients and 11 non-TB patients. The gene discussed is IFNG; the disease is tuberculosis.