Negative IFN-γ release assay (QFT-plus) results i.e. lack of IFN-γ production in response to TB antigens, in three participants that had confirmed TB episodes (PID03, PID08 and PID11) are a clear indication that there is a defect related to IFN-γ production in response to TB antigenic stimulation. Here, IFNG is linked to tuberculosis.