An autosomal recessive immunodeficiency caused but mutation(s) in the ITK gene, encoding tyrosine-protein kinase ITK/TSK. It is characterized by the early childhood onset of Epstein-Barr virus (EBV)-associated immune dysregulation leading to lymphoma, lymphomatoid granulomatosis, hemophagocytic lymphohistiocytosis, and/or hypogammaglobulinemia. [from
NCI]