MSMD is classified into two types, where autosomal MSMD is linked to defects in five autosomal genes (IFNGR1, IFNGR2, STAT1, IL12RB1 and IL12B) involved in the interleukin 12/23 dependant interferon γ (IFN-γ)-mediated immune response [94]. This evidence concerns the gene IL12B and Mendelian susceptibility to mycobacterial diseases.