Interferon gamma release assays (IGRAs), which uses enzyme-linked immunospot assay (ELISPOT assay) to quantitatively detect the level of interferon released by the peripheral blood mononuclear cells stimulated by Mycobacterium tuberculosis (Mtb) specific antigen, are new techniques widely used in the diagnosis of TB, T cells are sensitized to Mycobacterium tuberculosis antigens and the activated effector T cells, both CD4+ and CD8+, produce the cytokine interferon gamma (IFN-γ) when stimulated by these antigens. The gene discussed is IFNG; the disease is tuberculosis.