Table 1.

Inborn errors of CTLA4 and their phenocopies.

	CTLA4 haploinsufficiency				CTLA4 checkpoint inhibitor
Main clinical phenotypes		%	Immune/histological phenotype	Ref.	All (%)	Grade 3-5 (%)	Immune/histological phenotype	Ref.
	Hypogammaglobulinemia	84%	Expanded T cells with upregulated of activation markers. Increased IL-4 and IFN-γ-producing CD4+ T cells. Impaired suppressive function by Tregs. Lymphocytic infiltration in multiple organs.	(1–3)	ND		Dermatologic: Skin T cells infiltrate. Gastrointestinal: Enterocolitis with neutrophilic, lymphocytic infiltrate and both. Hypophysitis: Autoantibodies against TSH, FSH and ACTH-secreting cells.
	Lymphoproliferation	73%			ND
	Respiratory tract manifestation	57-68%			1-11%	1-2.7%		(28–30)
	Autoimmune cytopenia	62%			<1%	<1%		(31)
	Gastrointestinal manifestation	59%			30-40%	7.6-17%		(32–34)
	Dermatologic manifestation	21-56%			44-59%	1-4%		(32, 33, 35, 36)
	Thyroiditis/Hypothyroidism	14%			1.5-9%	0-1%		(32, 33)
	Liver manifestation	12%			3.8-8%	1%		(29, 32, 33)
	Hypophysitis	1%			13%	5%		(33, 37)

ND, Not Detectable.