Heterozygosity for loss-of-function mutations of CTLA4 and biallelic LRBA mutations each result in impaired tTreg function and syndromic autoimmunity, either CTLA4 haploinsufficiency with autoimmune infiltration (CHAI) or LRBA deficiency with autoantibodies, Treg defects, autoimmune infiltration, and enteropathy (LATAIE), respectively [110, 144–146] . The gene discussed is CTLA4; the disease is autoimmune lymphoproliferative syndrome due to CTLA4 haploinsufficiency.