Recently, interferon-gamma based assays (IGRA) to detect specific cellular immune response to antigens expressed in M. tuberculosis (ESAT-6: early secretory antigenic target 6, and CFP-10: culture filtrate protein 10), but absent in BCG and many environmental mycobacteria, have been reported to improve sensitivity and specificity for the diagnosis of TB [10-12]. The gene discussed is IFNG; the disease is tuberculosis.