Accumulating evidence indicates that QuantiFERON-TB Gold (QFT-G) assays, which detect interferon (IFN)-γ secreted by T-cells stimulated with M. tuberculosis (Mtb)-specific antigens, offer higher specificity than tuberculin skin test (TST) in detecting LTBI or active TB within a BCG-vaccinated population [8–9]. The gene discussed is IFNG; the disease is tuberculosis.