IFNG and Mendelian susceptibility to mycobacterial diseases: From a theoretical perspective, the finding that MSMD can be caused by mutations in IL12RB2, IL23R or SPPL2A and that these mutations are associated with impaired production of IFNγ—a requisite of anti-mycobacterial immunity—implies that IFNγ administration could be therapeutically beneficial in these clinical settings [51, 52].