IFNG and susceptibility to pneumonia measurement: Whereas, Canetti strains induced limited pneumonia with sustained expression of TNF-α.27,29 Likewise, other investigators showed a different level of cytokines production [TNF-α, IFN-γ] in patients infected with genetically distinct M. tuberculosis subtypes.12 Our results showed no association between the frequencies of SNPs in host and various lineages of M. tuberculosis. As shown in table 5, the TNF-α 238A and 857C alleles were associated with susceptibility to TB infection, but their distribution was almost equal among patient infected with different subtypes of M. tuberculosis.