CTLA4 Deficiency

**Semantic type:** Disease or Syndrome

**Definition:** A genetic condition caused by mutation(s) in the CTLA4 gene, encoding cytotoxic T-lymphocyte protein 4. Cytotoxic T-lymphocyte protein 4 is an inhibitory receptor acting as a negative regulator of T-cells, and two functional copies of the gene are required for normal immune function. Clinically, it may be characterized by gastrointestinal symptoms, lymphadenopathy, hepatomegaly, and splenomegaly, and autoimmune disorders. Mutations(s) in CTLA4 are also associated with autoimmune lymphoproliferative syndrome, type V.

**Synonyms:** - CHAI - CTLA4 Haploinsufficiency - CTLA4 haploinsufficiency