Up to now, eleven MSMD-causing genes, including nine autosomal (IFNGR1, IFNGR2, STAT1, IL12B, IL12RB1, ISG15, IRF8, RORC and TYK2 and two X-linked (NEMO, and CYBB) genes have been identified [1, 3, 4]. The gene discussed is IFNGR1; the disease is Mendelian susceptibility to mycobacterial diseases.