Since 1996, germline mutations in seven autosomal (IFNGR1, IFNGR2, IL12B, IL12RB1, STAT1, IRF8, ISG15) and two X-linked (NEMO, CYBB) genes have been discovered in MSMD patients [8,52–55]. This evidence concerns the gene IFNGR1 and Mendelian susceptibility to mycobacterial diseases.