Mendelian susceptibility to mycobacterial infection in man

Selective susceptibility to poorly pathogenic mycobacteria, such as bacille Calmette—Guérin vaccine and environmental non-tuberculous mycobacteria, has long been suspected to be a mendelian disorder but its molecular basis has remained elusive. Recently, recessive mutations in the interferon-γ-receptor ligand-binding chain, interferon-γ-receptor signalling chain, IL-12 p40 subunit and IL-12-receptor β1 chain genes have been identified in a number of patients with disseminated mycobacterial infection. Although genetically distinct, these conditions are immunologically related and highlight the essential role of interferon-γ-mediated immunity in the control of mycobacteria in man.