Autosomal dominant immune dysregulation syndrome in humans with CTLA4 mutations

D Schubert, C Bode, R Kenefeck, TZ Hou, JB Wing… - Nature medicine, 2014 - nature.com
D Schubert, C Bode, R Kenefeck, TZ Hou, JB Wing, A Kennedy, A Bulashevska…
Nature medicine, 2014nature.com
The protein cytotoxic T lymphocyte antigen-4 (CTLA-4) is an essential negative regulator of
immune responses, and its loss causes fatal autoimmunity in mice. We studied a large family
in which five individuals presented with a complex, autosomal dominant immune
dysregulation syndrome characterized by hypogammaglobulinemia, recurrent infections and
multiple autoimmune clinical features. We identified a heterozygous nonsense mutation in
exon 1 of CTLA4. Screening of 71 unrelated patients with comparable clinical phenotypes …
Abstract
The protein cytotoxic T lymphocyte antigen-4 (CTLA-4) is an essential negative regulator of immune responses, and its loss causes fatal autoimmunity in mice. We studied a large family in which five individuals presented with a complex, autosomal dominant immune dysregulation syndrome characterized by hypogammaglobulinemia, recurrent infections and multiple autoimmune clinical features. We identified a heterozygous nonsense mutation in exon 1 of CTLA4. Screening of 71 unrelated patients with comparable clinical phenotypes identified five additional families (nine individuals) with previously undescribed splice site and missense mutations in CTLA4. Clinical penetrance was incomplete (eight adults of a total of 19 genetically proven CTLA4 mutation carriers were considered unaffected). However, CTLA-4 protein expression was decreased in regulatory T cells (Treg cells) in both patients and carriers with CTLA4 mutations. Whereas Treg cells were generally present at elevated numbers in these individuals, their suppressive function, CTLA-4 ligand binding and transendocytosis of CD80 were impaired. Mutations in CTLA4 were also associated with decreased circulating B cell numbers. Taken together, mutations in CTLA4 resulting in CTLA-4 haploinsufficiency or impaired ligand binding result in disrupted T and B cell homeostasis and a complex immune dysregulation syndrome.
nature.com