Since the identification of the first genetic etiology of this syndrome in 1996, nine morbid genes (IFNGR1, IFNGR2, IRF8, STAT1, CYBB, NEMO, IL12B, IL12RB1 and ISG15) and 17 different genetic etiologies of MSMD have been discovered. Here, IL12RB1 is linked to Mendelian susceptibility to mycobacterial diseases.