An autosomal recessive disorder characterized by severe infantile inflammatory bowel disease manifesting as bloody diarrhea and failure to thrive, global developmental delay, epilepsy, brain atrophy and encephalopathy. Affected individuals suffer from recurrent infections associated with impaired T-cell response to stimulation and decreased T-cell subsets, including regulatory and helper T cells. The disease is inflammatory bowel disease, immunodeficiency, and encephalopathy (EFO_0010258).