IFNG and tuberculosis: The A allele and the AA genotype had been associated with low IFN-γ expression and susceptibility to TB in several populations around the world (Lio et al., 2002; Lopez-Maderuelo et al., 2003; Amim et al., 2008; Pacheco and Moraes, 2009; Mosaad et al., 2010; Prabhu Anand et al., 2010; Hashemi et al., 2011).