Mendelian susceptibility to mycobacterial disease (MSMD) is a rare genetic disease. It is a primary immunodeficiency featured by molecular defects in IL12/IFNγ dependent signalling pathway, leading to increased susceptibility to local or disseminated infections by environmental mycobacteria, Mycobacterium bovis Bacille Calmette-Guerin strain, nontyphoidal and typhoidal Salmonella serotypes.