Autosomal dominant (AD) mendelian susceptibility to mycobacterial diseases (MSMD) due to partial interferon gamma receptor 1 (IFN-gammaR1) deficiency is a genetic variant of MSMD (see this term) characterized by a partial deficiency leading to impaired IFN-gamma immunity and, consequently, recurrent, moderately severe infections with bacillus Calmette-Guérin (BCG) and other environmental mycobacteria (EM).