IL12RB1 and Mendelian susceptibility to mycobacterial diseases: Interleukin-12 receptor β1 (IL12RB1) deficiency, is the most common genetic etiology of MSMD, which is characterized by the selective predisposition to clinical disease caused by weakly-virulent mycobacteria, such as Bacillus Calmette-Guérin (BCG) vaccines, and environmental non-tuberculous mycobacteria (NTM).