IFNGR1 and infection: Most commonly, patients with complete IFN-γR1 deficiency present with lymphadenopathy, hepatosplenomegaly and intermittent fever in early childhood, caused by infection with weakly virulent, mostly environmental mycobacteria such as Mycobacterium avium or the vaccine strain Mycobacterium bovis bacillus Calmette-Guérin (BCG) [2].