Enrichment of Rare Variants of Hemophagocytic Lymphohistiocytosis Genes in Systemic Juvenile Idiopathic Arthritis.

Objective: To evaluate whether there is an enrichment of rare variants in familial hemophagocytic lymphohistiocytosis (HLH) genes and systemic juvenile idiopathic arthritis (sJIA) with or without macrophage activation syndrome (MAS). Methods: Targeted sequencing of HLH genes (LYST, PRF1, RAB27A, STX11, STXBP2, UNC13D) was performed in sJIA subjects from an established cohort. Sequence data from control subjects were obtained in silico (dbGaP:phs000280.v8.p2). Rare variant association testing (RVT) was performed with sequence kernel association test (SKAT) package. Significance was defined as p<0.05 after 100,000 permutations. Results: Sequencing data from 524 sJIA cases were jointly called and harmonized with exome-derived target data from 3000 controls. Quality control operations produced a set of 481 cases and 2924 ancestrally-matched control subjects. RVT of sJIA cases and controls revealed a significant association with rare protein-altering variants (minor allele frequency [MAF]<0.01) of STXBP2 (p=0.020), and ultra-rare variants (MAF<0.001) of STXBP2 (p=0.007) and UNC13D (p=0.045). A subanalysis of 32 cases with known MAS and 90 without revealed significant association of rare UNC13D variants (p=0.0047). Additionally, sJIA patients more often carried ≥2 HLH variants than did controls (p=0.007), driven largely by digenic combinations involving LYST. Conclusion: We identified an enrichment of rare HLH variants in sJIA patients compared with healthy controls, driven by STXBP2 and UNC13D. Biallelic variation in HLH genes was associated with sJIA, driven by LYST. Only UNC13D displayed enrichment in patients with MAS. This suggests that HLH variants may contribute to the pathophysiology of sJIA, even without MAS.

Features predicting colchicine efficacy in treatment of children with undefined systemic autoinflammatory disease: A retrospective cohort study.

OBJECTIVE: Patients with undefined systemic autoinflammatory diseases (uSAIDs) are challenging to manage, as there are no guidelines or recommendations for targeted therapy. We aimed to evaluate the efficacy of empiric treatment with colchicine in our single-center uSAID population in the United States, as well as the patient characteristics associated with the most robust colchicine response. METHODS: Children with uSAID 18 years old at initial evaluation during 2000-2019 were included if they received 3 months of colchicine therapy. Data on demographics, clinical features, laboratory/ genetic studies, and treatment responses were collected. Most statistics were based on chi-square analyses for categorical data. Complete response to colchicine was defined as resolution of episodes or the presence of minor residual symptoms that did not require any further therapy. A partial response was defined as a decrease in the frequency, severity, or length of episodes but still necessitating additional therapy. Patients were considered nonresponders if they did not experience any improvement with colchicine at target therapeutic dosing. RESULTS: We identified 133 children diagnosed with uSAID who met our inclusion criteria. The median time to starting empiric colchicine was 5 months from the diagnosis of autoinflammatory disease. 92.5% (n = 123) of patients had a beneficial response to colchicine, including 46.6% (n = 62) partial responders and 45.9% (n = 61) complete responders. The presence of a nonurticarial rash was associated with an incomplete colchicine response (29.2% (n = 21) vs 13.1% (n = 8), P = .025). The presence of a heterozygous MEFV mutation in patients who did not fit Familial Mediterranean Fever diagnostic criteria (n = 25) appeared to be associated with a greater likelihood of complete colchicine response, although this was not statistically significant (62.5% (n = 14) vs 42.6% (n =11), P = .08). In MEFV mutation-negative patients, a nonurticarial rash was even more strongly associated with incomplete colchicine response, with an OR of 27.53 (CI [1.59-477], P = .023). The presence of oral ulcers also corresponded to incomplete colchicine response, although this did not reach clinical significance (38.9% (n = 28) vs 24.6% (n = 15), P = .08). There was no significant association between episode duration or frequency and colchicine response. CONCLUSION: Colchicine leads to clinical benefits in most children with uSAID. We, thus, recommend an early trial of colchicine in newly diagnosed patients with uSAID.

Consensus treatment plans for periodic fever, aphthous stomatitis, pharyngitis and adenitis syndrome (PFAPA): a framework to evaluate treatment responses from the childhood arthritis and rheumatology research alliance (CARRA) PFAPA work group.

BACKGROUND: Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome is the most common periodic fever syndrome in children. There is considerable heterogeneity in management strategies and a lack of evidence-based treatment guidelines. Consensus treatment plans (CTPs) are standardized treatment regimens that are derived based upon best available evidence and current treatment practices that are a way to enable comparative effectiveness studies to identify optimal therapy and are less costly to execute than randomized, double blind placebo controlled trials. The purpose of this project was to develop CTPs and response criteria for PFAPA. METHODS: The CARRA PFAPA Working Group is composed of pediatric rheumatologists, infectious disease specialists, allergists/immunologists and otolaryngologists. An extensive literature review was conducted followed by a survey to assess physician practice patterns. This was followed by virtual and in-person meetings between 2014 and 2018. Nominal group technique (NGT) was employed to develop CTPs, as well as inclusion criteria for entry into future treatment studies, and response criteria. Consensus required 80% agreement. RESULTS: The PFAPA working group developed CTPs resulting in 4 different treatment arms: 1. Antipyretic, 2. Abortive (corticosteroids), 3. Prophylaxis (colchicine or cimetidine) and 4. Surgical (tonsillectomy). Consensus was obtained among CARRA members for those defining patient characteristics who qualify for participation in the CTP PFAPA study. CONCLUSION: The goal is for the CTPs developed by our group to lead to future comparative effectiveness studies that will generate evidence-driven therapeutic guidelines for this periodic inflammatory disease.