Haploinsufficiency Of A20 Research Articles

A20 haploinsufficiency disturbs immune homeostasis and drives the transformation of lymphocytes with permissive antigen receptors.

Genetic TNFAIP3 (A20) inactivation is a classical somatic lymphoma lesion and the genomic trait in haploinsufficiency of A20 (HA20). In a cohort of 34 patients with HA20, we show that heterozygous TNFAIP3 loss skews immune repertoires toward lymphocytes with classical self-reactive antigen receptors typically found in B and T cell lymphomas. This skewing was mediated by a feed-forward tumor necrosis factor (TNF)/A20/nuclear factor κB (NF-κB) loop that shaped pre-lymphoma transcriptome signatures in clonally expanded B (CD81, BACH2, and NEAT1) or T (GATA3, TOX, and PDCD1) cells. The skewing was reversed by anti-TNF treatment but could also progress to overt lymphoma. Analysis of conditional TNFAIP3 knock-out mice reproduced the wiring of the TNF/A20/NF-κB signaling axis with permissive antigen receptors and suggested a distinct regulation in B and T cells. Together, patients with the genetic disorder HA20 provide an exceptional window into A20/TNF/NF-κB-mediated control of immune homeostasis and early steps of lymphomagenesis that remain clinically unrecognized.

Immunodeficiency 70 (IMD 70)

Background: Immunodeficiency 70 is a rare disease and there are only very few cases in the literature. Case History: Young boy in his early 20’s from Indian subcontinent presented with recurrent episodes of fever, oral ulcers, loss of weight for past 3 years. Four episodes (july 2019, april 2020, APRIL 2021, Jan 2022) of fever, each high grade associated with chills, rigor, nausea, myalgia, throat pain, holo-cranial headache, painful oral ulcers over the tongue and painless over lips. Initial episode of fever was associated with leucopenia (3200) and thrombocytopenia (122000), acute kidney injury (creatinie-3.0) and pyelonephritis, transaminitis. He received 2 weeks of parenteral antibiotics and improved. Subsequent episodes of fever is not associated with any localizing symptoms or signs. No history Suggestive of connective tissue disease. Family history was non contributory. Physical examination: He was febrile (101 degree F), pulse rate 100/minute, respiratory rate 18/minute, tongue ulceration in lateral border, no lymphadenopathy, no organomegaly, normal sytemic examination. Evaluation: The patient was evaluated for chronic infections, hematalogical malignancy, Behcet’s disease, auto inflammatory syndromes like Haplo insufficiency of A20. His complete blood count, electrolytes, renal function test, liver function test urine microscopy, blood culture were normal. CRP was elevated (58 mg/l). Tzanck smear from buccal mucosa was negative. CT thorax and abdomen showed no significant lymphadenopathy, organomegaly, evidence of infections or malignancy. In view of oral ulcers & fever Behcet’s disease was considered and HLA b51 was sent and came negative. Exome genome sequencing was done to diagnose immunodeficiency or autoinflammatory syndromes which came positive for immunodeficiency 70. Treatment: He was treated with colchicine and fever subsided and leucopenia improved Discussion: Immunodeficiency-70 (IMD70) is an autosomal dominant immunologic disorder characterized by severe cutaneous warts on the hands, feet, and face, suggesting increased susceptibility to human papillomavirus (HPV) infection. Affected individuals may also have recurrent bacterial infections like pneumonia, boils, sinusitis, as well as feature of autoinflammation, such as colitis, celiac disease, and retinal vasculitis. Laboratory studies show decreased CD4+ T cells and decreased CD19+ B cells; hypogammaglobulinemia, combined T cell and B cell immunodeficiency characterized by decreased CD4+ T cells, decreased CD19+ B cells, recurrent bacterial infections, and severe cutaneous warts on the hands, feet, and face that has material basis in heterozygous mutation in IVNS1ABP on chromosome 1q25.3.

Haploinsufficiency of A20 caused by a novel pathogenic missense variant of TNFAIP3 and successfully treated with anti-TNF and immunosuppressive therapies

Loss-of-function of protein A20, encoded by TNFAIP3, leads to an early-onset haploinsufficiency of A20 (HA20). This study reports one Chinese child with HA20 and explores the genetic etiology of TNFAIP3 variant. The patient exhibited transient recurrent episodes of fever, intermittent signs of arthritis, gastrointestinal symptoms and multiple colonic ulcers. Laboratory tests revealed elevated inflammatory indicators and mild to moderate anemia. Genetic analysis identified a heterozygous de novo variant in his TNFAIP3 gene (c.740C＞T, p. P247L), which had never been reported before. The novel missense variation was validated to be pathogenic through causing insufficient expression of A20, over-activation of NF-κB signaling pathway and elevated levels of proinflammatory cytokines in response to stimulation by lipopolysaccharide. A combination of oral corticosteroids, TNF-α inhibitors and thalidomide freed him from symptoms and abnormal inflammatory indicators. Furthermore, continual improvement of the patient's condition was observed during a follow-up period of five months. We demonstrate a case with a de novo missense variant resulting in a loss-of-function of TNFAIP3, which expands the clinical spectrum of HA20. Cytokine antagonists and immunosuppressants may be effective drugs.

Clinical analysis of 49 cases of non-inflammasome related conditions

Objective: To summarize the clinical characteristics and provide clues for early identification of non-inflammasome related conditions. Methods: The clinical manifestations, laboratory tests, genetic testing and follow-up of 49 children with non-inflammasome related conditions in Peking Union Medical College Hospital from January 2006 to February 2022 were retrospectively analyzed. Results: A total of 49 children, 29 of them were boys and 20 were girls. The age of onset was 0.8 (0.3, 1.6) years, the age at diagnosis was 5.7 (2.8, 8.8) years, and the time from onset to diagnosis was 3.6 (1.9, 6.3) years. Combined with genetic testing results, 49 children with non-inflammasome related conditions were found, including 34 cases (69%) of Blau syndrome, 4 cases (8%) of tumour necrosis factor receptor-associated periodic syndrome, 4 cases (8%) of haploinsufficiency of A20, 2 cases (4%) of Majeed syndrome, 2 cases (4%) of pyogenic sterile arthritis, pyoderma gangrenosum, acne syndrome and 3 cases (6%) of chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature syndrome. There were 22 cases (45%) with a positive family history. The clinical manifestations included 37 cases (76%) cases with rash, 38 cases (78%) with joint involvement, 33 cases (67%) with eye involvement, 17 cases (35%) with recurrent fever. In addition, 11 cases (22%) were complicated with digestive system involvement. Thirty cases (61%) presented as elevated inflammatory indexes (erythrocyte sedimentation rate and (or) C-reactive protein), positive autoantibodies were noticed in 3 cases (6%). The patients were treated with glucocorticoid in 23 cases (47%), immunosuppressive agents in 43 cases (88%) and biologic agents in 37 cases (76%). During the follow-up of 5.8 (2.9, 8.9) years, 3 cases (6%) died. Conclusions: The symptoms of non-inflammasome related conditions include recurrent fever, rash, joint and ocular involvement with increased inflammatory indexes and negative autoantibodies. Up to now, glucocorticoids, immunosuppressants and biologic agents are the most popular medications for the non-inflammasome related conditions.

Interstitial lung disease in autoinflammatory disease in childhood: A systematic review of the literature.

The lung is one of the target organs in the systemic involvement of autoinflammatory disease (AID), and interstitial lung disease (ILD) is the primary phenotype of lung involvement in AID. In this review, we aimed to conduct a systematic review of the available literature to highlight ILD in AID. We conducted a systematic literature search in PubMed/MEDLINE and Scopus from the inception of the databases to January 2022. References were first screened by title and then by abstract by two authors. Eighteen original papers were selected for full-text review. During the literature search, we identified 18 relevant articles describing 52 cases of AID and ILD. Of those, 44 patients had stimulator of interferon genes-associated vasculopathy with onset in infancy (SAVI), six had coatomer protein complex (COPA) syndrome, one had haploinsufficiency of A20, and one had mevalonate kinase deficiency. Pulmonary fibrosis, cyst formation, and ground glass areas were the most common findings in chest tomography of patients with COPA syndrome and SAVI. Janus kinase inhibitors were used to treat most of the patients with SAVI, which stabilized ILD. ILD should be considered carefully in children with AID, especially those with interferonopathy.

TNFAIP3 mutation causing haploinsufficiency of A20 with a hemophagocytic lymphohistiocytosis phenotype: a report of two cases

BackgroundA20 haploinsufficiency (HA20) is a newly introduced autosomal dominant autoinflammatory disorder, also known as Behcet’s-like disease. Some of the most common symptoms of the disease are recurrent oral, genital, and/or gastrointestinal (GI) ulcers, episodic fever, musculoskeletal symptoms, cutaneous lesions, and recurrent infections. Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition of multi-organ failure due to excessive immune activation. HLH has been reported in a few HA20 patients. Herein, we report two children with the primary presentation of HLH, with a mutation in TNFAIP3, in favor of HA20.Case presentationsOur first patient was a 4-month-old boy who presented with fever, irritability, pallor, and hepatosplenomegaly. Pancytopenia, elevated ferritin, and decreased fibrinogen levels were found in laboratory evaluation. He was diagnosed with HLH and was treated with methylprednisolone and cyclosporine. Two years later, whole exome sequencing (WES) indicated a mutation in TNFAIP3 at NM_001270507: exon3: c.C386T, p.T129M, consistent with A20 haploinsufficiency. Etanercept, a TNF inhibitor, was prescribed, but the parents were reluctant to initiate the therapy. The patient passed away with the clinical picture of cerebral hemorrhage.The second patient was a 3-month-old boy who presented with a fever and hepatosplenomegaly. Laboratory evaluation found pancytopenia, hyperferritinemia, hypoalbuminemia, hypertriglyceridemia, and hypofibrinogenemia. With the establishment of the HLH diagnosis, he was treated with etoposide, dexamethasone, and cyclosporine, and recovered. WES results revealed a heterozygous de novo variant of TNFAIP3 (c. T824C in exon 6, 6q23.3) that leads to a proline to leucine amino acid change (p. L275P). He was treated with etanercept and has been symptom-free afterward.ConclusionsThis report is a hypothesis for developing of the HLH phenotype in the presence of TNFAIP3 mutation. Our results provide a new perspective on the role of TNFAIP3 mutation in HLH phenotypes, but more extensive studies are required to confirm these preliminary results.

AB1300 AA AMYLOIDOSIS IN A PATIENT WITH MUTATIONS IN BOTH ADA2 AND A20 GENES

BackgroundAdenosine Deaminase 2 Deficiency (DADA2) and Haploinsufficiency of A20 (HA20) are two recently described monogenic autoinflammatory diseases (AID). The uncontrolled inflammatory response has been associated with an increased risk of AA amyloidosis in other AID, but there are only two reported patients with DADA2-related amyloidosis so far.1,2ObjectivesWe herein report a patient with AA amyloidosis and AID associated with both DADA2 and HA20.MethodsWe used the Ion Torrent platform for deep sequencing.ResultsCase: A 20-year-old male patient born to consanguineous parents (Figure 1), was admitted to our hospital with fever and abdominal pain in June 2014. Peritonitis, hepatomegaly, and a palpable non-tender mass in the right axillary cavity were detected in physical examination, and his laboratory investigations revealed neutrophilic leukocytosis, high acute phase reactants (APR), and nephrotic range proteinuria. CT angiography showed multiple thrombotic microaneurysms in celiac, splenic, superior, and inferior mesenteric and bilateral renal arteries; and MRI documented an additional aneurysm in anterior communicating artery. No finding was detected in hepatitis serology. He had been diagnosed with polyarteritis nodosa, and prednisolone and azathioprine were started. Renal histopathology confirmed the AA amyloidosis. Genetic analysis revealed no pathogenic MEFV variant. Colchicine and anakinra 100 mg/day were added to his treatment. He experienced 1-2 abdominal episodes annually between 2014-2019, and APR were normal between attacks. In March 2019, he was admitted to the hospital because of abdominal pain, high APR, and iron deficiency anemia. No gross pathology was observed in endoscopic examination of gastrointestinal tract, but histopathological investigation of the gastric mucosa and terminal ileum showed AA amyloidosis. Multiple aneurysms were detected in renal arteries with angiography. Deep sequencing of the targeted genes revealed homozygous p.Pro251Leu in ADA2 gene and heterozygous p.Thr647Pro in TNFAIP3 gene encoding A20, confirming the molecular diagnosis of DADA2 and HA20. The patient described oral recurrent aphthous ulcers starting from his childhood, but he had no uveitis or genital ulcers. His mother and brother also had recurrent oral aphthous ulcers. Genetic analyses showed heterozygous p.Pro251Leu variant in ADA2 gene in his mother, and heterozygous p.Gln703Lys variant in NLRP3 gene as well as heterozygous p.Thr647Pro TNFAIP3 variant and heterozygous p.Pro251Leu ADA2 in his brother. An improvement in his findings was observed within 2 weeks after switching his anakinra to adalimumab 40 mg every other week. At his last visit in February 2021, the patient had no complaints with normal APR, and urinalysis analysis showed 200 mg/day proteinuria, which was regressed from 3 g/day.ConclusionThis is the first case of AA amyloidosis associated with ADA2 and TNFAIP3 (A20) variants. ADA2 p.Pro251Leu variant has previously been validated as likely pathogenic, and our patient’s clinical findings were mainly compatible with DADA2. On the other hand, TNFAIP3 gene p.Thr647Pro mutation has been reported as variant of unknown significance, but it may have contributed to the DADA2 associated increased risk of amyloidosis. A better response of proteinuria to adalimumab treatment indicates superiority of anti-TNFs in DADA2 patients compared to anti-IL-1 drugs.

Novel loss-of-function mutations in TNFAIP3 gene in patients with lupus nephritis.

Heterozygous loss-of-function mutations in the tumour necrosis factor alpha induced protein 3 (TNFAIP3) gene cause an early-onset auto-inflammatory disease named haploinsufficiency of A20 (HA20). Here we describe three unrelated patients with autoimmune lupus nephritis (LN) phenotypes carrying three novel mutations in the TNFAIP3 gene. Whole-exome sequencing (WES) was used to identify the causative mutations in three biopsy-proven LN patients. Sanger sequencing and quantitative polymerase chain reaction (qPCR) were used to validate the mutations identified by WES. RNA sequencing, qPCR and cytometric bead array was used to detect inflammatory signatures in the patients. The patients predominantly presented with an autoimmune phenotype, including autoimmune haemolytic anaemia, multipositive autoantibodies and LN. Additionally, novel phenotypes of allergy and pericardial effusion were first reported. WES identified three novel heterozygous mutations in the TNFAIP3 gene, including a novel splicing mutation located in the canonical splicing site (c.634+2T>C)resulting in an intron 4 insertion containing a premature stop codon, a de novo novel copy number variation (exon 7-8 deletion) and a novel nonsense mutation c.1300_1301delinsTA causing a premature stop codon. We further identified hyperactivation signatures of nuclear factor- kappa B and type I IFN signalling and overproduction of pro-inflammatory cytokines in the blood. This report expanded the phenotype to a later age, as two girls were diagnosed at age 3 years and one man at age 29 years. Kidney involvement may be the main feature of the clinical spectrum of HA20, even in adults. Genetic screening should be considered for early-onset LN patients.

POS-442 NOVEL LOSS-OF-FUNCTION MUTATIONS IN TNFAIP3 GENE CAUSE HUMAN LUPUS NEPHRITIS

Heterozygous loss-of-function mutations in the TNFAIP3 gene cause an early-onset autoinflammatory disease named haploinsufficiency of A20 (HA20). HA20 was also identified in patients with childhood-onset autoimmune diseases and autoimmune lymphoproliferative syndrome. SLE is not only the most common systemic autoimmune disease, but also one of the most heterogeneous illnesses presenting immense challenges to diagnosis and treatment. More than 30 causative genes for monogenic SLE and lupus-like syndrome have been described, which are associated with complement component, interferon, NF-kB, self-tolerance, and other yet uncharacterized pathways.

Dysregulation of the Intestinal Microbiome in Patients With Haploinsufficiency of A20.

IntroductionHaploinsufficiency of A20 (HA20) is a form of inborn errors of immunity (IEI). IEIs are genetically occurring diseases, some of which cause intestinal dysbiosis. Due to the dysregulation of regulatory T cells (Tregs) observed in patients with HA20, gut dysbiosis was associated with Tregs in intestinal lamina propria.MethodsStool samples were obtained from 16 patients with HA20 and 15 of their family members. Infant samples and/or samples with recent antibiotics use were excluded; hence, 26 samples from 13 patients and 13 family members were analyzed. The 16S sequencing process was conducted to assess the microbial composition of samples. Combined with clinical information, the relationship between the microbiome and the disease activity was statistically analyzed.ResultsThe composition of gut microbiota in patients with HA20 was disturbed compared with that in healthy family members. Age, disease severity, and use of immunosuppressants corresponded to dysbiosis. However, other explanatory factors, such as abdominal symptoms and probiotic treatment, were not associated. The overall composition at the phylum level was stable, but some genera were significantly increased or decreased. Furthermore, among the seven operational taxonomic units (OTUs) that increased, two OTUs, Streptococcus mutans and Lactobacillus salivarius, considerably increased in patients with autoantibodies than those without autoantibodies.DiscussionDetailed interaction on intestinal epithelium remains unknown; the relationship between the disease and stool composition change helps us understand the mechanism of an immunological reaction to microorganisms.

Identification of a Novel Mutation in TNFAIP3 in a Family With Poly-Autoimmunity.

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.

A novel missense mutation in TNFAIP3 causes haploinsufficiency of A20

A20, encoded by TNFAIP3, is an effective anti-inflammatory molecule that plays a crucial role in inhibiting NF-κB signal transmission and is linked to multiple inflammatory diseases. It has been reported that the haploinsufficiency of A20 (HA20) caused by multiple base mutations in TNFAIP3 shows early-onset spontaneous Behçet-like disease. However, the mechanisms by which A20 mutations involved in inflammatory disease are incompletely defined. Herein, we reported a novel TNFAIP3 (c.1804A > T, p.T602S) variation, which has not been reported before. Summarizing the patient's immunodeficiency phenotype, we aimed to delineate the underlying mechanism for regulation of inflammation and immunity. Candidate genes associated with the Behçet-like phenotypes of the patient were screened and identified by using whole-exome and sanger sequencing. Functional studies were performed in A20(c.1804A > T, p.T602S) patient-derived peripheral blood mononuclear cells (PBMCs) and THP-1 cell lines by lentivirus mediating stable over-expression of A20 and A20(c.1804A > T, p.T602S) to analyze the activity of NF-κB signaling pathway. The clinical manifestations in patients with syndrome are Behçet-like disorder, and sequencing revealed heterozygous mutation in TNFAIP3 (c.1804A > T, p.T602S). Functional tests found that the PBMCs of the patient and his family carrying this heterozygous variant stimulated by LPS, TNF-α, or IL-1β, increased the levels of inflammatory factors and induced over-activation of the canonical NF-κB signaling pathway. Similar results were also observed in the stable transduction THP-1 (A20, c.1804A＞T) cell line stimulated by LPS, TNF-α or IL-1β. The novel loss-of-function A20 variation (c.1804A > T, p.T602S) causes over-activation of the canonical NF-κB signaling pathway and fail to terminate NF-κB signaling in response to stimulation by inflammatory cytokines. The variation triggers a dominantly-inherited Behçet-like disorder caused by haploinsufficiency of the A20 protein. Identification of the novel A20 mutation attaches great importance to prenatal diagnosis and fetal therapeutic intervention, drastically reducing the risk of newborns suffering from HA20.

M144 TNFAIP3 DEFICIENCY AS AN UNCOMMON CAUSE OF HYPOGAMMAGLOBULINEMIA

Heterozygous variants in TNFAIP3 cause an autosomal dominant haploinsufficiency of A20 (HA20). HA20 presents as an autoinflammatory disease characterized by oral/genital ulcers, recurrent fevers, skin lesions, gastrointestinal ulcers, and autoimmunity. While there is increasing recognition of monogenetic etiologies of common variable immunodeficiency (CVID), this has not been classically described in TNFAIP3 deficiency. We present a case of HA20 presenting atypically as CVID and inflammatory bowel disease (IBD). This case demonstrates the importance of broad evaluation for monogenetic etiology in primary immunodeficiency as every patient does not present with a “classic presentation”.

Clinical characteristics and genetic analysis of A20 haploinsufficiency

PurposeTo evaluate the clinical and genetic characteristics of 3 children with Haploinsufficiency of A20 (HA20). Methods:The clinical and genetic testing data of 3 children with HA20 treated at Capital Institute of Pediatrics (CIP) between August 2016 and October 2019 were retrospectively analysed.ResultPatient 1 presented with arthritis and inflammatory bowel disease, patient 2 presented with axial spinal arthritis and lupus-like syndrome, and patient 3 presented with recurrent oral ulcers, gastrointestinal ulcers, and perianal abscesses. Regarding laboratory tests, patients were found to have elevated white blood cell (WBC) count, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). The CRP and ESR was reported to be high in all the patients. The WBC was reported to be high in patient 1 and 3. Patient 2 was positive for antinuclear antibodies, anti-Sjögren’s syndrome antigen A, dsDNA, rheumatoid factor and Coombs test. Genetic testing showed that all three patients had heterozygous mutation in TNFAIP3 gene. As for the treatment, patient 1 was treated with TNFα antagonist, patient 2 was treated with TNF α antagonist and sulfasalazine, and patient 3 was treated with corticosteroids and thalidomide. Patients 1 and 2 were followed for four and 3 months, respectively. There was an improvement in joint and gastrointestinal symptoms; inflammatory indices and rheumatoid factor (RF) were normal, and dsDNA and Coombs test became negative. Patient 3 was treated at another hospital and showed gradual improvement in oral ulcers and perianal abscesses.ConclusionHA20 is a single-gene auto-inflammatory disease caused by mutation in tumour necrosis factor (TNF)-α-induced protein 3 (TNFAIP3) gene. It may present as Behçet-like syndrome and resemble various other autoimmune diseases as well. Corticosteroids and immunosuppressive agents are effective treatments, and cytokine antagonists can be used in refractory cases. Whole-exome genetic testing should be proactively performed for children with early-age onset or Behçet-like syndrome to achieve early diagnosis and accurate treatment.

Systematic evaluation of nine monogenic autoinflammatory diseases reveals common and disease-specific correlations with allergy-associated features

BackgroundMonogenic autoinflammatory diseases (AID) are caused by mutations in innate immune genes. The effects of these mutations on allergic inflammation are unknown.ObjectivesWe investigated allergic, immunological and clinical phenotypes in FMF...

TNFAIP3 Plays a Role in Aging of the Hematopoietic System.

Hematopoietic stem and progenitor cells (HSPC) experience a functional decline in response to chronic inflammation or aging. Haploinsufficiency of A20, or TNFAIP3, an innate immune regulator, is associated with a variety of autoimmune, inflammatory, and hematologic malignancies. Based on a prior analysis of epigenomic and transcriptomic changes during normal human aging, we find that the expression of A20 is significantly reduced in aged HSPC as compared to young HSPC. Here, we show that the partial reduction of A20 expression in young HSPC results in characteristic features of aging. Specifically, heterozygous deletion of A20 in hematopoietic cells resulted in expansion of the HSPC pool, reduced HSPC fitness, and myeloid-biased hematopoiesis. These findings suggest that altered expression of A20 in HSPC contributes to an aging-like phenotype, and that there may be a common underlying mechanism for diminished HSPC function between inflammatory states and aging.

A20 Haploinsufficiency in a Chinese Patient With Intestinal Behcet's Disease-Like Symptoms: A Case Report

Objective: Intestinal Behcet's disease (iBD) is an autoimmune disorder diagnosed by typical intestinal ulcers and systemic Behcet's disease (BD) manifestations. Haploinsufficiency of A20 (HA20) is a recently described autoinflammatory disease with a phenotype resembling BD, caused by heterozygous loss-of-function mutations in TNFAIP3 gene (encoding A20).Methods: We described a 29-year-old female with iBD-like symptoms including relapsing ulceration of intestinal anastomosis, recurrent oral ulcers and vasculitis in extremities. Due to the atypical intestinal ulcers with long segmental involvement and intestinal obstruction, whole exome sequencing (WES) was performed to screen for the underlying genetic defect and the identified gene was confirmed by Sanger sequencing. The expression levels of A20 was evaluated by Western blot. Sanger sequencing and Western blot were also performed in the patient's family members.Results: A heterozygous mutation of TNFAIP3 (c.305A>G, p. Asn 102 Ser) was identified in the patient. The identical TNFAIP3 mutation was also found in her father and brother who had suffered from recurrent oral ulcers since childhood. Functional experiments revealed that the expression of A20 was decreased in the peripheral blood mononuclear cells of the patient and her family members who carried the TNFAIP3 mutation.Conclusion: We described a Chinese patient with a novel heterozygous mutation in TNFAIP3 who developed iBD-like symptoms. We proposed that the TNFAIP3 heterozygous mutation (c.305A>G, p. Asn 102 Ser) with an insufficient expression of A20 may be associated with the iBD phenotype in patients.

Haploinsufficiency of A20 Due to Novel Mutations in TNFAIP3.

Haploinsufficiency of A20 (HA20) is a newly described immune dysregulation disease due to the loss-of-function mutation in TNFAIP3. In the present study, we report six patients from four unrelated Chinese families with distinct pathogenic mutations in TNFAIP3, including three novel variants. All of the patients presented with early-onset autoimmune/auto-inflammatory diseases, including Crohn's disease, Behcet's disease, systemic lupus erythematosus, and unclassified auto-inflammatory syndrome. Immunological phenotype tests showed elevated levels of serum pro-inflammatory cytokines, reduced naïve B cells and TFH cells, an inverted CD4:CD8 ratio, and increased susceptibility to restimulation-induced cell death (RICD) and FASL-induced apoptosis in derived T cells. Insufficient expression of A20 was found in these patients. A20 truncated protein was detected in mutant-transfected 293T cells. Upon TNF-α stimulation, the NF-κB pathway was over-activated in both derived T cells of these patients and mutant-transfected Hela cells. In conclusion, clinical manifestations are diverse in patients with HA20, even in those with the same TNFAIP3 mutation. A20 inhibits the NF-κB pathway and plays a crucial role in the regulation of cell death. Haploinsufficiency of A20 leads to defects in both innate and adaptive immunity.

Paediatric-onset haploinsufficiency of A20 associated with a novel and de novo nonsense TNFAIP3 mutation

Paediatric-onset haploinsufficiency of A20 associated with a novel and de novo nonsense TNFAIP3 mutation

Immunophenotyping of A20 haploinsufficiency by multicolor flow cytometry

Haploinsufficiency of A20 (HA20) causes inflammatory disease resembling Behçet's disease; many cases have been reported, including some that are complicated with autoimmune diseases. This study aims to clarify the immunophenotype of patients with HA20 by analyzing lymphocyte subsets using multicolor flow cytometry. The patients with HA20 previously diagnosed in a nationwide survey were compared by their cell subpopulations. In total, 27 parameters including regulatory T cells (Tregs), double-negative T cells (DNTs), and follicular helper T cells (TFHs) were analyzed and compared with the reference values in four age groups: 0–1, 2–6, 7–19, and ≥20 years. The Tregs of patients with HA20 tended to increase in tandem with age-matched controls at all ages. In addition, patients ≥20 years had increased DNTs compared with controls, whereas TFHs significantly increased in younger patients. In HA20 patients, the increase in DNTs and TFHs may contribute to the development of autoimmune diseases.