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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 1. examining genes known to cause monogenic immunodeficiency, autoinflammation or vasculitis by virtual panel application; 2. scrutiny of variants prioritised by Exomiser using Human Phenotype Ontology (HPO); 3. identification of copy number variants using ExomeDepth; and 4. 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: 5 cases of Haploinsufficiency of A20 with novel TNFAIP3 variants (p.T76I, p.M112Tfs*8, p.S548Dfs*128, p.C657Vfs*14, p.E661Nfs*36); 1 case of ISG15 deficiency with a novel nonsense variant (ISG15:p.Q16X) and 1p36.33 microdeletion; 1 case of Common variable immune deficiency (TNFRSF13B:p.A181E); and 2 cases of TNF receptor associated periodic syndrome (TNFRSF1A:p.R92Q). Of the remaining 22 patients, 8 (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, since this has impact on choice of therapy, prognosis, and genetic counselling., (© The Author(s) 2023. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Objectives: Hereditary systemic autoinflammatory diseases are rare genetic disorders, which if untreated, can be complicated by AA amyloidosis leading to renal failure and premature death. Our objective was to find a genetic cause in a British family with a dominantly inherited autoinflammatory disease complicated by AA amyloidosis., Methods: The index patient and his sister underwent comprehensive clinical and laboratory assessment including the next-generation sequencing panel targeting autoinflammatory genes. Subsequently, other relatives underwent clinical evaluation and genetic testing. Screening of the SAA1 gene was performed in all symptomatic cases., Results: The index case and his sister presented with proteinuria due to AA amyloidosis. They have been suffering from episodes of fever accompanied by severe abdominal and chest pain, arthritis and erythema since childhood. Their father died aged 52 years from complications following a cadaveric renal transplantation. The post-mortem examination demonstrated AA amyloidosis. The index case's grandmother, two paternal cousins and two of their children described similar symptoms. All symptomatic individuals had excellent responses to colchicine. Next-generation sequencing analysis identified a single MEFV p.P373L variant in the index case, his sister and subsequently, in symptomatic family members. Sequencing of the SAA1 gene revealed all cases were heterozygous for the SAA1.1 allele., Conclusion: Typically FMF is an autosomal recessive disorder; nonetheless rare cases of dominantly inherited disease have previously been described. Here we report a novel MEFV variant p.P373L, causing dominant FMF complicated by AA amyloidosis in four generations of a British family., (© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: Monogenic autoinflammatory disorders (AID) and primary immunodeficiencies can present early in life with features that may be mistaken for Behçet's disease (BD). We aimed to retrospectively describe the clinical and laboratory features of 11 paediatric cases referred for suspected BD who turned out to have an alternative, monogenic disease mimicking BD., Methods: Retrospective, paediatric BD specialist multicentre case series. Next generation sequencing (NGS) or conventional candidate gene screening approaches were utilized, facilitated in some cases by functional assays., Results: Eleven children referred with suspected BD underwent genetic screening because of atypical BD features, and/or presentation before age 5 years. Eight patients (73%) were Caucasian, two were Pakistani and one was Turkish; 55% were female. A positive family history of BD was reported in 54% cases. The median age of disease onset was 0.6 (range 0.2-2.3) years. All had systemic inflammation and oral ulceration; 5/11 had genital ulceration; 3/11 had ocular involvement; and 9/11 had cutaneous manifestations. Nine/11 had known disease-causing genetic mutations in: TNFAIP3 (n = 2), WDR1 (n = 2), NCF1, AP1S3, LYN, MEFV and GLA. The remaining two cases each had novel variants in STAT1 and TNFRSF1A., Conclusion: Rare monogenic diseases can mimic BD, particularly when presenting early in life. These observations are now informing a strategy to explore screening for genetic mimics of BD in a UK cohort of children and adults to better understand the proportion of UK BD patients who may in fact have an underlying monogenetic diagnosis., (© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: The aim was to carry out a retrospective review of the efficacy and safety of anakinra in paediatric patients with undifferentiated autoinflammatory disease (uAID)., Methods: We carried out a retrospective study of children with uAID at a single quaternary centre. The clinical efficacy of anakinra was evaluated using physician global assessment (PGA) and serological response assessed by levels of serum amyloid A and CRP. Safety was assessed by exploring adverse events, including infection and drug reactions., Results: This study included 22 patients, 64% females and 36% males of median age 7.1 years (range 0.13-14.11 years), with uAID. The median starting dose of anakinra was 2 mg/kg (range 2-6 mg/kg) and the median duration of treatment 19.6 months (range 0.8-100 months). Before anakinra treatment, the median PGA, on a three-point Likert scale, was 2 (range 1-2), which fell to 1 (range 0-2) within 3 months of treatment. Eight of 22 (36%) patients achieved complete clinical and serological remission; 8/22 (36%) achieved a partial response; and 6/22 (28%) had no response to anakinra. Adverse events included death (3/22, 14%) and allogeneic haematopoietic stem cell transplantation (1/22, 5%). There were no new safety signals, and anakinra was well tolerated overall., Conclusion: Retrospectively, 72% of children with uAID responded well to anakinra, with 36% achieving full clinical and serological remission within 3 months. This suggests that empirical trials of IL-1 blockade might be warranted in children with uAID. Clear stopping criteria based on predefined parameters should be considered, because non-responders required alternative therapies, facilitated by a definitive molecular diagnosis where possible.

Objective: The role of the adaptive immune system has not been explored in detail compared with the innate immune system in systemic JIA (sJIA) pathogenesis. The aim of this study was to examine the phenotype of circulating peripheral blood CD4(+) T-cell subpopulations in a cross-sectional study of sJIA patients during disease remission on medication and during acute flare of the disease., Methods: Flow cytometry was used to examine the phenotype and cytokine production of IFNγ-, IL-4- and IL-17-producing CD4(+) T cells in the peripheral blood of 10 sJIA patients with active disease, 9 sJIA with inactive disease, 14 JIA patients with oligoarticular onset, 10 adult control subjects and 10 age-matched control subjects. In parallel, we examined the proportion of FoxP3(+) Tregs., Results: IFNγ- and IL-17-producing CD4(+) T cells and IL-17-producing CD3(+)CD4(-) T cells were present at higher proportions in the peripheral blood of sJIA patients, irrespective of their disease status. Our data also confirm the known increase of the proportions of IFNγ-producing Th1 cells with increasing age and suggest an increase with age in the IL-17-producing CD4(+) T-cell population., Conclusion: This study is the first to describe significantly higher proportions of Th1 and Th17 T helper cell subsets in the peripheral blood of sJIA patients. These proinflammatory cells may play a pathogenic role in sJIA. Our data also emphasize the importance of using paediatric age-matched control subjects when evaluating the T-cell cytokine profile in JIA.