ISG15 and Mendelian susceptibility to mycobacterial diseases: In humans, biallelic mutations in ISG15 were reported to result in an impaired IFN-γ mediated immunity, leading to an increase predisposition to mycobacterial infections in most cases, as also observed in patients with Mendelian Susceptibility to Mycobacterial Diseases (MSMD) [4]; [5]; [6] (see Additional file 1: Table S2).