autoimmune lymphoproliferative syndrome due to CTLA4 haploinsufficiency (MONDO_0014493) is a somatic mutation in the CTLA4 gene resulting in only a single functional gene. Haploinsufficiency for CTLA4 is associated with autoimmune lymphoproliferative syndrome, type V. Also known as: ALPS due to CTLA4 haploinsufficiency, ALPS type 5, ALPS type V, CHAI, CTLA-4 haploinsufficiency with autoimmune infiltration disease, CTLA4 haploinsufficiency, autoimmune lymphoproliferative syndrome type 5, autoimmune lymphoproliferative syndrome type V.