Paediatric Behçet's Disease: A Comprehensive Review with an Emphasis on Monogenic Mimics

Genetic testing of Behçet's disease using next-generation sequencing to identify monogenic mimics and HLA-B*51

OBJECTIVE

Several monogenic autoinflammatory disorders and primary immunodeficiencies can present early in life with features that may be mistaken for Behçet's disease (BD). We aimed to develop a genetic analysis workflow to identify rare monogenic BD-like diseases and establish the contribution of HLA haplotype in a cohort of patients from the UK.

METHODS

Patients with clinically suspected BD were recruited from four BD specialist care centres in the UK. All participants underwent whole-exome sequencing (WES), and genetic analysis thereafter by (i) examining genes known to cause monogenic immunodeficiency, autoinflammation or vasculitis by virtual panel application; (ii) scrutiny of variants prioritized by Exomiser using Human Phenotype Ontology (HPO); (iii) identification of copy number variants using ExomeDepth; and (iv) HLA-typing using OptiType.

RESULTS

Thirty-one patients were recruited: median age 15 (4-52), and median disease onset age 5 (0-20). Nine/31 (29%) patients had monogenic disease mimicking BD: five cases of Haploinsufficiency of A20 with novel TNFAIP3 variants (p.T76I, p. M112Tfs*8, p. S548Dfs*128, p. C657Vfs*14, p. E661Nfs*36); one case of ISG15 deficiency with a novel nonsense variant (ISG15: p.Q16X) and 1p36.33 microdeletion; one case of common variable immune deficiency (TNFRSF13B: p.A181E); and two cases of TNF receptor-associated periodic syndrome (TNFRSF1A: p.R92Q). Of the remaining 22 patients, eight (36%) were HLA-B*51 positive.

CONCLUSION

We describe a novel genetic workflow for BD, which can efficiently detect known and potentially novel monogenic forms of BD, whilst additionally providing HLA-typing. Our results highlight the importance of genetic testing before BD diagnosis, as this has an impact on choice of therapy, prognosis and genetic counselling.

British Association of Dermatologists and British Society for Rheumatology living guideline for managing people with Behçets 2024

The overall objective of the guideline is to provide up-to-date, evidence-based recommendations for the management of Behçets. The document aims to offer an appraisal of all relevant literature up to 25 August 2023 focusing on any key developments; to address important, practical clinical questions relating to the primary guideline objective; and to provide guideline recommendations and appropriate research recommendations.

Cellular and molecular basis of proximal small intestine disorders

The proximal part of the small intestine, including duodenum and jejunum, is not only dedicated to nutrient digestion and absorption but is also a highly regulated immune site exposed to environmental factors. Host-protective responses against pathogens and tolerance to food antigens are essential functions in the small intestine. The cellular ecology and molecular pathways to maintain those functions are complex. Maladaptation is highlighted by common immune-mediated diseases such as coeliac disease, environmental enteric dysfunction or duodenal Crohn's disease. An expanding spectrum of more than 100 rare monogenic disorders inform on causative molecular mechanisms of nutrient absorption, epithelial homeostasis and barrier function, as well as inflammatory immune responses and immune regulation. Here, after summarizing the architectural and cellular traits that underlie the functions of the proximal intestine, we discuss how the integration of tissue immunopathology and molecular mechanisms can contribute towards our understanding of disease and guide diagnosis. We propose an integrated mechanism-based taxonomy and discuss the latest experimental approaches to gain new mechanistic insight into these disorders with large disease burden worldwide as well as implications for therapeutic interventions.

Challenges and opportunities in transitional care process in Behçet's syndrome

Behçet's syndrome (BS) is a rare chronic multi-systemic inflammatory disorder that usually involves adults between third and fourth decades of life, while pediatric and juvenile onset are relatively rare. BS young patients (YP) often develop a full-blown disease late after onset, requiring careful diagnostic workup and regular follow-up while they grow up. In this regard, the purpose of transitional programs is to ensure continuous high-quality care to YP with chronic conditions, providing them with the skills necessary to become independent and empowered adults able to chronically self-manage their disease. EULAR/PReS released the first set of standards and recommendations for transitional care (TC) of YP with juvenile-onset rheumatic diseases, but the appropriate timing for transition, the tools to evaluate patients' readiness, and indicators of transition plans effectiveness still need to be identified. Although little is known regarding TC in BS, it is easy to assume that BS YP will benefit from developmentally and disease-specifically appropriate transition plans, which may promote continuity of care, improve perceived quality of life and prevent poor disease outcomes. This perspective article discusses the key concepts and the goals of TC, addressing the potential challenges and opportunities of TC for YP with BS in clinical practice.

Behçet's syndrome: recent advances to aid diagnosis

Behçet's syndrome is a recurring inflammatory multiorgan disorder affecting the skin, mucosa, eyes, joints, stomach, and central nervous system. Behçet's syndrome epidemiology varies greatly among populations (0.64-420/100,000), and Behçet's syndrome has gained increasing international acclaim in the recent 50 years due to raising awareness of the syndrome, although it is rare in most population. In addition to the unclear etiology of the syndrome, the diagnosis of Behçet's syndrome is complicated by a vague clinical presentation, phenotypic heterogeneity and/or incomplete representation, and the lack of any specific laboratory, radiographic, or histological findings. There exists a dire need to elucidate factors that contribute to disease pathogenesis and/or are associated with clinical features of Behçet's syndrome and the classification of different forms of the syndrome. The identification of such molecular, cellular, and/or clinical factors are crucial for timely diagnosis and efficacious management of Behçet's syndrome. We discuss recent advances in the clinical diagnosis of Behçet's syndrome and related contributions of genetics, epigenetics, microbiome, inflammasomes, and autoantibodies to the improved diagnosis, management, and understanding of Behçet's syndrome.

Treatment Options in Pediatric Behçet's Disease

Behçet's disease is a rare and poorly understood vasculitis affecting blood vessels of all types and sizes. Uveitis and oral and genital ulcers represent the typical clinical triad. Populations along the ancient trading route connecting the Mediterranean basin with the Middle and Far East are most affected. Up to a quarter of the cases has a pediatric onset, typically around puberty. The aim of the treatment is early intervention to control inflammation, with symptom relief and prevention of relapses, damage, and complications. The heterogeneous clinical presentation often requires a multidisciplinary and tailored approach. Ocular, neurological, gastrointestinal, and vascular involvement is associated with a worse prognosis and needs more aggressive treatments. In young patients with expected prolonged disease, treatment should also focus on preventive measures and lifestyle advice. In recent years, the pharmacological armamentarium has grown progressively, although only a limited number of drugs are currently authorized for pediatric use. Most evidence for these drugs still derives from adult studies and experience; these are prescribed as off-label medications and are only available as adult formulations. Corticosteroids frequently represent the mainstay for the management of the initial acute phases, but their potential serious adverse effects limit their use to short periods. Different conventional disease-modifying anti-rheumatic drugs have long been used. Many other biologic drugs targeting different cytokines such as interleukin-1, interleukin-6, and interleukin-17 and treatments with small molecules including the phosphodiesterase 4 and Janus kinase inhibitors are emerging as novel promising therapeutic agents. In recent years, a growing interest has developed around anti-tumor necrosis factor agents that have often proven to be effective in severe cases, especially in those with a gastrointestinal and ocular involvement.

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

BACKGROUND

A20 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 PRESENTATIONS

Our 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.

CONCLUSIONS

This 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.

The eyes have it: when skin findings prompt referral to ophthalmology

PURPOSE OF REVIEW

Co-presentation of ocular and cutaneous conditions is common and prompt recognition of known associations may be imperative to sight-saving intervention. There are currently limited reviews in the pediatric literature addressing comorbid ocular and dermatologic presentations. Recent diagnostic and therapeutic advances have drastically altered the prognostic landscape for several disease states when recognition and referral are timely. The aim of this report is to examine important oculocutaneous disease associations with emphasis on management of ocular complications and appropriate referral practices to ophthalmology specialists.

RECENT FINDINGS

Oculocutaneous associations can be broadly classified into four etiologic categories: infectious, inflammatory, genetic, and medication/nutrition induced pathology. Several conditions in all four categories have had recent advances in their etiologic understanding, diagnostic evaluation, and therapeutic approach. Thematically, these advances highlight increasing disease prevalence of certain conditions, previously unrecognized pediatric relevance of others, updated diagnostic criteria, and newer categories of iatrogenic illness induced by advances in medical therapy.

SUMMARY

This review is designed to provide the pediatric practitioner a vignette-based high-level overview of both common and sight threatening associations that should prompt consideration for ophthalmology consultation. Conditions were selected based on relevance, relative urgency, and recent advances in their etiologic/therapeutic understanding.

Skin manifestations of inborn errors of NF-κB

More than 400 single gene defects have been identified as inborn errors of immunity, including many arising from genes encoding proteins that affect NF-κB activity. We summarise the skin phenotypes in this subset of disorders and provide an overview of pathogenic mechanisms. NF-κB acts cell-intrinsically in basal epithelial cells during differentiation of skin appendages, influences keratinocyte proliferation and survival, and both responses to and amplification of inflammation, particularly TNF. Skin phenotypes include ectodermal dysplasia, reduction and hyperproliferation of keratinocytes, and aberrant recruitment of inflammatory cells, which often occur in combination. Phenotypes conferred by these rare monogenic syndromes often resemble those observed with more common defects. This includes oral and perineal ulceration and pustular skin disease as occurs with Behcet's disease, hyperkeratosis with microabscess formation similar to psoriasis, and atopic dermatitis. Thus, these genotype-phenotype relations provide diagnostic clues for this subset of IEIs, and also provide insights into mechanisms of more common forms of skin disease.