A very rare group of disorders where a person without an immune deficiency is susceptible to infection by weak mycobacterial organisms, nontuberculous and environmental mycobacteria e.g. Calmette-Guerin Bacillus (BCG). The severity of the disorder is greatly variable and ranges from a localized recurring non-tuberculous mycobacterial infection to a potentially fatal BCG infection. Most people who are infected with these organisms have no symptoms but a genetic mutation in some people makes them more susceptible. See also Mendelian susceptibility to atypical mycobacteria