Haploinsufficiency of A20 and other paediatric inflammatory disorders with mucosal involvement

Clinical updates in inborn errors of immunity: a focus on the noninfectious clinical manifestations

PURPOSE OF REVIEW

In the last 5 years, several new inborn errors of immunity (IEI) have been described, especially in the areas of immune dysregulation and autoinflammation. As a result, the clinical presentation of IEIs has broadened. We review the heterogeneous presentation of IEIs and detail several of the recently described IEIs with a focus on the noninfectious manifestations commonly seen.

RECENT FINDINGS

IEIs may present with early onset and/or multiple autoimmune manifestations, increased risk for malignancy, lymphoproliferation, severe atopy, autoinflammation and/or hyperinflammation. Because of this, patients can present to a wide array of providers ranging from primary care to various pediatric subspecialists. The International Union of Immunological Societies (IUIS) expert committee has created a phenotypic classification of IEIs in order to help clinicians narrow their evaluation based on the laboratory and clinical findings.

SUMMARY

Both primary care pediatricians and pediatric subspecialists need to be aware of the common clinical features associated with IEI and recognize when to refer to allergy-immunology for further evaluation. Early diagnosis can lead to earlier treatment initiation and improve clinical outcomes for our patients.

Genetic Defects in Early-Onset Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) represents a spectrum of disease, which is characterized by chronic gastrointestinal inflammation. Monogenic mutations driving IBD pathogenesis are more highly represented in early-onset compared to adult-onset disease. The pathogenic genes which dysregulate host immune responses in monogenic IBD affect both the innate (ie, intestinal barrier, phagocytes) and adaptive immune systems (ie, T cells, B cells). Advanced genomic and targeted functional testing can improve clinical decision making and present increased opportunities for precision medicine approaches in this important patient population.

The spectrum of clinical presentation in haploinsufficiency of A20; a case report of a novel mutation in TNFAIP3 gene

Haploinsufficiency of A20 was first described in 2016 as a new autoinflammatory disease that clinically presents as early-onset Behcet's disease. After the publication of the first 16 cases, more patients were diagnosed and described in the literature. The spectrum of clinical presentation has expanded. In this short report, we present a patient with a novel mutation in the TNFAIP3 gene. The clinical presentation included signs of an autoinflammatory disease with recurrent fever, abdominal pain, diarrhea, respiratory tract infections, and elevated inflammatory parameters. We will emphasize the importance of genetic testing, especially in patients with various clinical signs that do not fit a single autoinflammatory disease.

Druggable monogenic immune defects hidden in diverse medical specialties: Focus on overlap syndromes

In the last two decades two new paradigms changed our way of perceiving primary immunodeficiencies: An increasing number of immune defects are more associated with inflammatory or autoimmune features rather than with infections. Some primary immune defects are due to hyperactive pathways that can be targeted by specific inhibitors, providing innovative precision treatments that can change the natural history of diseases. In this article we review some of these “druggable” inborn errors of immunity and describe how they can be suspected and diagnosed in diverse pediatric and adult medicine specialties. Since the availability of precision treatments can dramatically impact the course of these diseases, preventing the development of organ damage, it is crucial to widen the awareness of these conditions and to provide practical hints for a prompt detection and cure.

Case Report: An early-onset inflammatory colitis due to a variant in TNFAIP3 causing A20 haploinsufficiency

Autoinflammatory diseases (AID) are a heterogeneous group of inherited conditions caused by abnormal activation of systems mediating innate immunity. Recent literature focuses on A20 Haploinsufficiency, an autoinflammatory disease with a phenotype resembling Behçet disease (BD). It is caused by loss-of-function mutations in TNFAIP3 gene that result in the activation of a pro-inflammatory pathway. In this case report we describe a one-year-old baby who came to our attention for hematochezia appeared at three months of age which was considered an expression of early-onset colitis. The following appearance of cutaneous inflammation Behçet-like and the positive family history concurred with the diagnosis of an autoinflammatory disease. Extended genetic tests in the patient allowed to identify a heterozygous variant in TNFAIP3 [NM_006290.4:c.460G > T, p.(Glu154Ter)], not previously described and not present in the GnomAD database. As a consequence the diagnosis A20 Haploinsufficiency was established and the appropriate management was started. The same TNFAIP3 variant was also found in her father who had suffered from recurrent oral aphthosis, vitiligo and thyroiditis since childhood. In conclusion, we described a young patient with a novel heterozygous mutation in TNFAIP3 who developed BD-like symptoms. We proposed that loss-of-function variants in TNFAIP3 may be associated with a very early-onset intestinal BD phenotype.

Haploinsufficiency of A20 in a Chinese child caused by loss-of-function mutations in TNFAIP3: A case report and review of the literature

CASE PRESENTATION

A 3-year-and-6-month-old child was reported to have recurrent high fever with generalized lymph node enlargement and significant elevation of inflammatory markers such as C-reactive protein and procalcitonin in tests. Later, whole exome sequencing determined that the child's disease was haploinsufficiency of A20 (HA20).

RESULTS

After immunosuppressive therapy, the child's symptoms improved significantly, and the inflammatory markers dropped to the normal range.

CONCLUSION

Because of the characteristics of HA20, this disease is often underdiagnosed and misdiagnosed in clinical practice. By reporting this case of HA20 in a child, we hope to increase the awareness of this disease in the clinic.

Neonatal Lupus Erythematosus as a Rare Cause of Fever in Young Infants

Neonatal lupus erythematosus (NLE) is a rare disease caused by passively transmitted autoantibodies from the mother. NLE is a multi-organ system disease characterized by cutaneous, cardiac, hematological, hepatobiliary, and neurological manifestations. This study aimed to review the various symptoms and clinical manifestations in young infants with NLE and their mothers. We conducted a retrospective review of medical records of patients with NLE who were both examined and treated at Pusan National University Children's Hospital between January 2009 and December 2020 and their mothers. Twenty-seven patients with NLE comprising 13 male patients (48.1%) and 14 female patients (51.9%) were included. The most common symptom was rash (40.7%), followed by fever (25.9%), arrhythmia (14.8%), splenomegaly (11.1%), and intrauterine growth retardation (7.4%). Seven patients with fever had various organ system manifestations, including cutaneous (100%), hematological (71.4%), hepatobiliary (57.1%), and central nervous system (CNS; 28.6%) manifestations. Two of the febrile patients had aseptic meningitis. Cutaneous, cardiac, hematological, hepatobiliary, and CNS involvement were noted in 44.4%, 18.5%, 51.9%, 40.7%, and 22.2% of the patients, respectively. Systemic lupus erythematosus (SLE) was the most common maternal disease (14/27, 51.9%). Ten mothers (37.0%) had not been diagnosed with any autoimmune disease until their babies were diagnosed. Among them, three were subsequently diagnosed with SLE, five were diagnosed with the Sjögren's syndrome, and two of them still had no known diagnosis of any autoimmune disorder. Fever is a common symptom of NLE; thus, when there is no clear focus of fever in infants, NLE needs to be considered, especially in cases with skin rashes.

Clinical characteristics and genetic analysis of A20 haploinsufficiency

PURPOSE

To 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.

RESULT

Patient 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.

CONCLUSION

HA20 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.

Immunity and Genetics at the Revolving Doors of Diagnostics in Primary Immunodeficiencies

Primary immunodeficiencies (PIDs) are a large and growing group of disorders commonly associated with recurrent infections. However, nowadays, we know that PIDs often carry with them consequences related to organ or hematologic autoimmunity, autoinflammation, and lymphoproliferation in addition to simple susceptibility to pathogens. Alongside this conceptual development, there has been technical advancement, given by the new but already established diagnostic possibilities offered by new genetic testing (e.g., next-generation sequencing). Nevertheless, there is also the need to understand the large number of gene variants detected with these powerful methods. That means advancing beyond genetic results and resorting to the clinical phenotype and to immunological or alternative molecular tests that allow us to prove the causative role of a genetic variant of uncertain significance and/or better define the underlying pathophysiological mechanism. Furthermore, because of the rapid availability of results, laboratory immunoassays are still critical to diagnosing many PIDs, even in screening settings. Fundamental is the integration between different specialties and the development of multidisciplinary and flexible diagnostic workflows. This paper aims to tell these evolving aspects of immunodeficiencies, which are summarized in five key messages, through introducing and exemplifying five clinical cases, focusing on diseases that could benefit targeted therapy.

Knee Joint Swelling at Presentation: A Case of Pediatric Crohn Disease With a TNFAIP3 Mutation

Crohn disease (CD) is a chronic inflammatory disease, and its incidence in children is rising. Despite extensive reports and investigations, the pathogenesis of CD has not been clearly elucidated, particularly in regard to triggering factors. A genetic predisposition is considered important when investigating the mechanism leading to CD, and the discovery of new CD-associated genes has increased our understanding of its immunopathogenesis and improved the efficacy of its treatment of CD. Early detection and treatment (eg, as children) with gene-based precision therapy can effectively prevent complications related to CD. In this case, a Chinese Han boy with CD associated with a mutation of tumor necrosis factor α-induced protein 3 was treated with recombinant human tumor necrosis factor-a receptor II:IgG Fc fusion protein. We suspected the boy had CD because of chronic abdominal pain, aphthous stomatitis, moderate anemia, a high erythrocyte sedimentation rate (36-79 mm/h), multiple intestinal ulcers, knee joint swelling, and a tumor necrosis factor α-induced protein 3 mutation. After total enteral nutrition and hormone therapy for 5 months, his abdominal pain and joint symptoms did not improve, so we started gene-based precision therapy with recombinant human tumor necrosis factor-a receptor II: IgG Fc fusion protein, which may play an important role in restricting TNF-α-induced NF-κB signaling. After 3 weeks, inflammation indicators were within the normal range, and multiple ulcers and joint symptoms were relieved. The present case demonstrates a safe therapeutic schedule that leads to rapid improvements in the clinical and biochemical status of patients with CD.

Cutaneous clues to diagnose autoinflammatory diseases

Systemic autoinflammatory diseases (AIDs) are a group of disorders characterized by recurrent episodes of systemic inflammation. Suspecting the diagnosis can be difficult and many of the clinical manifestations are common to different diseases. Although most of the cutaneous manifestations are non-specific, it is important to know them because sometimes they can lead to the diagnosis. The purpose of this review was to synthesize the main cutaneous lesions of autoinflammatory diseases to aid in their diagnosis.

The First Case of an Infant with Familial A20 Haploinsufficiency in Korea

Haploinsufficiency of A20 (HA20) is a newly described autoinflammatory disease caused by loss-of-function mutations in the TNFAIP3 gene. Clinical phenotypes are heterogenous and resemble Behçet's disease, juvenile idiopathic arthritis, inflammatory bowel disease, or periodic fever syndrome, with symptoms developing at an early age. Here, we report the first case of infantile familial HA20 in Korea, which mimics neonatal lupus erythematosus (NLE). A 2-month-old infant exhibited symptoms including recurrent fever, erythematous rashes, and oral ulcers, with elevated liver enzymes, and tested positive for several autoantibodies, similar to systemic lupus erythematosus (SLE); therefore, she was suspected to have NLE. However, six months after birth, symptoms and autoantibodies persisted. Then, we considered the possibility of other diseases that could cause early onset rashes and abnormal autoantibodies, including autoinflammatory syndrome, monogenic SLE, or complement deficiency, all of which are rare. The detailed family history revealed that her father had recurrent symptoms, including oral and genital ulcers, knee arthralgia, abdominal pain, and diarrhea. These Behcet-like symptoms last for many years since he was a teenager, and he takes medications irregularly only when those are severe, but doesn't want the full-scale treatment. Whole-exome sequencing was conducted to identify a possible genetic disorder, which manifested as pathogenic variant nonsense mutation in the TNFAIP3 gene, leading to HA20. In conclusion, HA20 should be considered in the differential diagnosis of an infant with an early-onset dominantly inherited inflammatory disease that presents with recurrent oral and genital ulcerations and fluctuating autoantibodies. Additionally, it also should be considered in an infant with suspected NLE, whose symptoms and abnormal autoantibodies persist.

Towards better diagnostic criteria for periodic fever, aphthous stomatitis, pharyngitis and adenitis syndrome

AIM

Periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis (PFAPA) syndrome is the most common cause of a periodic fever in childhood. The exact pathogenesis and the aetiology of PFAPA are still unknown.

METHODS

We conducted a non-systematic review of published articles about PFAPA syndrome and summarised the evidence for diagnostic criteria and treatment options for PFAPA.

RESULTS

The first proposed diagnostic criteria for PFAPA, in addition to periodic fever, included aphthous stomatitis, pharyngitis or cervical lymphadenitis in children younger than five years at the beginning of the symptoms. C-reactive protein (CRP) levels and leucocyte counts increase in most patients during episodes. Recent research reveals that tonsillectomy provides an immediate and long-lasting cure for PFAPA, even in the absence of classic criteria of aphthous stomatitis, pharyngitis or cervical adenitis and in children older than five years.

CONCLUSION

We suggest that PFAPA can be diagnosed in children with at least five regularly occurring fever episodes without any other explanation, even in the absence of aphthous stomatitis, pharyngitis or cervical lymphadenitis and also in children older than five years.