CTLA4 and hyperinsulinemic hypoglycemia, familial, 4: Functional CTLA4 deficiency, whether due to CTLA4 haploinsufficiency, LRBA deficiency or DEF6 deficiency, may be suspected in cases with lymphoproliferation (38–73%) and granulomatous disorders (17–45%) associated with complex autoimmunity (mainly cytopenias) and inflammatory enteropathy.