IFNγR1 deficiency presenting with visceral leishmaniasis and Mycobacterium Avium infections mimicking HLH.

Interferon gamma receptor-1 (IFNγR1) deficiency is a rare inborn error of immunity. It can be inherited as an autosomal recessive (AR), partial or complete, or autosomal dominant (AD) trait and exhibits high allelic variability. Biallelic deleterious recessive variants of IFNGR1 that result in absent expression or defective downstream signaling of IFNγR1, cause failure to activate macrophages in response to interferon-gamma (IFN-γ), rendering innate immunity ineffective in clearing intracellular pathogens.