To date, 21 genes involved in Type II IFN immunity have been implicated in MSMD, 18 autosomal (IFNGR1, IFNGR2, IFNG, STAT1, JAK1, IRF8, IRF1, SPPL2A, TYK2, IL12B, IL12RB1, IL12RB2, IL23R, TBX21, RORC, ZNFX1, ISG15 and USP18) and three X-linked (CYBB, NEMO and MCTS1) [6, 30, 33, 38]. Here, IFNG is linked to Mendelian susceptibility to mycobacterial diseases.