Patients with interleukin-2-inducible T-cell kinase (ITK) deficiency is prone to lymphoproliferative diseases, including Hodgkin and non-Hodgkin lymphoma, EBV lymphoproliferative disease, and hemophagocytic lymphohistiocytosis [30]. The gene discussed is ITK; the disease is hyperinsulinemic hypoglycemia, familial, 4.