Abstract
Haploinsufficiency of A20 (HA20) is an inflammatory disease caused by mutations in the TNFAIP3 gene classically presenting with Behcet’s-like disease. A20 acts as an inhibitor of inflammation through its effect on NF-kB pathway. Here we describe four consanguineous patients (three sisters and their mother) with a predominantly autoimmune phenotype, including thyroiditis, type I diabetes, hemolytic anemia and chronic polyarthritis. All patients had recurrent oral ulcers, with only 1 patient presenting also recurrent fever episodes, as a classical autoinflammatory feature. Next generation sequencing identified a novel heterozygous frameshift mutation (p.His577Alafs*95) that causes a premature stop codon in the zinc finger domain of A20, leading to a putative haploinsufficiency of the protein. Functional analyses confirmed the pathogenicity of the mutation. The variant was associated with decreased levels of A20 in blood cells. Accordingly, ex-vivo lipopolysaccharide (LPS)-stimulated patients’ peripheral blood mononuclear cells (PBMCs) showed higher levels of p65 NF-kB phosphorylation, as well as increased production of the proinflammatory cytokines IL-1β, IL-6 and TNF-α. Moreover, in agreement with recent observations, demonstrating a role for A20 in inhibiting STAT1 and IFNγ pathways, markedly higher circulating levels of the two IFNγ-inducible chemokines CXCL9 and CXCL10 were detected in all patients. Supporting the findings of a hyperactivation of IFNγ signaling pathway in HA20 patients, patients’ monocytes showed higher levels of STAT1 without stimulation, as well as higher phosphorylated (active) STAT1 levels following IFNγ stimulation. In conclusion, our study show that in the clinical spectrum of HA20 autoimmune features may predominate over autoinflammatory features and demonstrate, from a molecular point of view, the involvement of A20 in modulating not only the NF-kB, but also the IFNγ pathway.
Highlights
A20 haploinsufficiency (HA20) has been described as an autosomal-dominant-inheritance autoinflammatory disease characterized by Behcet’s-like disease symptoms, such as recurrent oral and genital ulcers and inflammatory bowel disease (IBD)-like pattern [1]
We studied an Italian family (Figure 1A) carrying a previously unreported mutation in the tumour necrosis factor-a-inducible protein 3 (TNFAIP3) gene leading to A20 haploinsufficiency
We describe the clinical features of four family members carrying a novel mutation in the TNFAIP3 gene leading to Haploinsufficiency of A20 (HA20)
Summary
A20 haploinsufficiency (HA20) has been described as an autosomal-dominant-inheritance autoinflammatory disease characterized by Behcet’s-like disease symptoms, such as recurrent oral and genital ulcers and inflammatory bowel disease (IBD)-like pattern [1]. Patient 2 (Pt2) is a 20 years old girl who was admitted to our hospital at the age of 9 because of Type 1 diabetes Her medical history included, similar to her sister, recurrent oral ulcers since early childhood. Patient 3 (Pt3) is a 13 year-old girl She presented oral ulcers since childhood, like her sisters, and reports recurrent febrile episodes associated with cervical lymphadenopathy, not related to infections, between the age of 6 and 8. Patient 4 (Pt4) is a 46 years old woman, the mother of the three girls described above She presented recurrent oral and genital painful ulcers since childhood, along with recurrent episode of acute abdominal pain, requiring occasional evaluations at the emergency department, with no definitive interpretation. Graphpad Prism 9 software was used for statistical analysis and graphs
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
