HAX1 and inborn error of immunity: This term is used for a heterogeneous group of primary immunodeficiencies including sporadic autosomal recessive, autosomal dominant and x-linked types (39) of which the autosomal recessive type with a homozygous mutation in antiapoptotic protein, HAX1, accounts for one third of these patients and has been identified as the only subtype associated with neurologic abnormalities (40).