Macrophage activation syndrome in patients with systemic juvenile idiopathic arthritis on anti-interleukin-1 or -6 therapy.

OBJECTIVES: The aim of this study is to investigate the effect of anti-interleukin (IL)-1/-6 biologics on systemic juvenile idiopathic arthritis (sJIA)-associated macrophage activation syndrome (MAS). METHODS: Demographic, clinical, and laboratory data of patients followed up with a diagnosis of sJIA-associated MAS assessed from sixteen pediatric rheumatology centers across the country. The clinical and laboratory features of MAS developing while on biological drugs were compared with those without this treatment. RESULTS: One hundred and sixty-two patients were included in the study. 45 of the MAS events were detected under the effect of anti-IL-1/-6 biologics, while the patients experiencing the remaining 155 events have not received biological treatment in the last three months. Platelet count [128 (72-232) vs 199 (130-371) 109/l], ferritin level on admission [1107 (676-2050) vs 2863 (1193-9562) ng/ml], C-reactive protein level [15.4 (2.9-56) vs 90 (32-160) mg/l], erythrocyte sedimentation rate [13 (3-36) vs 43.5 (13-77) mm/h] and fever duration [5 (4-7.5) vs 10 (7-14.3) days] were found lower in the group under the impact of anti-IL-1/-6 biologics. Among patients treated with biologics, 26.6% did not meet the published 2016 MAS classification criteria at presentation. The rates of hepatomegaly and splenomegaly were relatively lower in the canakinumab-treated group when compared with those receiving other biologicals or to patients, not on biologicals. CONCLUSION: Anti-IL-1/-6 therapies can mask the clinical and laboratory features of MAS, and proposed guidelines for MAS classification criteria may not be met.

Towards a standardized program of transitional care for adolescents with juvenile idiopathic arthritis for Turkey: a national survey study.

BACKGROUND: Juvenile idiopathic arthritis (JIA) is a prevalent childhood chronic arthritis, often persisting into adulthood. Effective transitional care becomes crucial as these patients transition from pediatric to adult healthcare systems. Despite the concept of transitional care being recognized, its real-world implementation remains inadequately explored. This study aims to evaluate the thoughts and practices of healthcare providers regarding transitional care for JIA patients. METHODS: A cross-sectional survey was conducted among pediatric and adult rheumatologists in Turkey. Based on the American Academy of Pediatrics' six core elements of transitional care, the survey included 86 questions. The respondents' demographic data, attitudes towards transitional care, and practical implementation were assessed. RESULTS: The survey included 48 rheumatologists, with 43.7% having a transition clinic. The main barriers to establishing transition programs were the absence of adult rheumatologists, lack of time, and financial constraints. Only 23.8% had a multidisciplinary team for transition care. Participants agreed on the importance of coordination and cooperation between pediatric and adult healthcare services. The timing of the transition process varied, with no consensus on when to initiate or complete it. Participants advocated for validated questionnaires adapted to local conditions to assess transition readiness. CONCLUSIONS: The study sheds light on the challenges and perspectives surrounding transitional care for JIA patients in Turkey. Despite recognized needs and intentions, practical implementation remains limited due to various barriers. Cultural factors and resource constraints affect the transition process. While acknowledging the existing shortcomings, the research serves as a ground for further efforts to improve transitional care and ensure better outcomes for JIA patients transitioning into adulthood.

A score for predicting colchicine resistance at the time of diagnosis in familial Mediterranean fever: data from the TURPAID registry.

OBJECTIVES: Colchicine forms the mainstay of treatment in FMF. Approximately 5-10% of FMF patients are colchicine resistant and require anti-IL-1 drugs. We aimed to compare the characteristics of colchicine-resistant and colchicine-responsive patients and to develop a score for predicting colchicine resistance at the time of FMF diagnosis. METHODS: FMF patients (0-18 years) enrolled in the Turkish Paediatric Autoinflammatory Diseases (TURPAID) registry were included. The predictive score for colchicine resistance was developed by using univariate/multivariate regression and receiver operating characteristics analyses. RESULTS: A total of 3445 FMF patients [256 (7.4%) colchicine-resistant and 3189 colchicine-responsive) were included (female:male ratio 1.02; median age at diagnosis 67.4 months). Colchicine-resistant patients had longer, more frequent attacks and were younger at symptom onset and diagnosis (P < 0.05). Fever, erysipelas-like erythema, arthralgia, arthritis, myalgia, abdominal pain, diarrhoea, chest pain, comorbidities, parental consanguinity and homozygosity/compound heterozygosity for exon 10 MEFV mutations were significantly more prevalent among colchicine-resistant than colchicine-responsive patients (P < 0.05). Multivariate logistic regression analysis in the training cohort (n = 2684) showed that age at symptom onset, attack frequency, arthritis, chest pain and having two exon 10 mutations were the strongest predictors of colchicine resistance. The score including these items had a sensitivity of 81.3% and a specificity of 49.1%. In the validation cohort (n = 671), its sensitivity was 93.5% and specificity was 53.8%. CONCLUSION: We developed a clinician-friendly and practical predictive score that could help us identify FMF patients with a greater risk of colchicine resistance and tailor disease management individually at the time of diagnosis.

Inflammatory comorbidities in the largest pediatric Familial Mediterranean fever cohort: a multicenter retrospective study of Pediatric Rheumatology Academy (PeRA)-Research Group (RG).

AIM: The aim of this study was to investigate the frequency and type of FMF-associated inflammatory diseases in a large FMF pediatric patients and to compare them to those FMF patients without concomitant inflammatory diseases. MATERIALS AND METHODS: Familial Mediterranean fever patients enrolled in the Pediatric Rheumatology Academy (PeRA)-Research Group (RG) were included. The patients were divided into two groups according to concomitant inflammatory disease as FMF patients who had a concomitant inflammatory disease (group 1) and FMF patients who did not have a concomitant inflammatory disease (group 1). The clinical findings and treatments were compared between the two groups. RESULTS: The study group comprised 3475 patients with FMF. There were 294 patients (8.5%) in group 1 and 3181 patients (91.5%) in group 2. Juvenile idiopathic arthritis (n = 136) was the most common accompanying inflammatory disease. Arthritis, M694V homozygosity, and the need for biological therapy were more frequently observed in Group 1 (p < 0.05). Fever and abdominal pain were more frequently detected in Group 2 (p < 0.05). FMF patients with concomitant inflammatory diseas more frequently demonstrated colchicine resistance. There were no significant differences in the median attack frequency, chest pain, amyloidosis, erysipelas-like erythema, or family history of FMF between the two patient groups. CONCLUSION: To the best of our knowledge, this is the largest pediatric cohort reviewed to date. FMF patients may have different clinical profiles and colchicine responses if they have with concomitant inflammatory diseases. Key points • FMF is associated with some inflammatory comorbidities diseases. • To the best of our knowledge, this is the largest cohort evlauated pediatric FMF associated inflammatory comorbidities diseases reviewed to date.

The safety of canakinumab in systemic juvenile idiopathic arthritis and autoinflammatory diseases in pediatric patients: a multicenter study.

OBJECTIVE: To evaluate the safety of canakinumab using real-world data in patients with systemic juvenile idiopathic arthritis (sJIA) and autoinflammatory diseases (AID). RESEARCH DESIGN AND METHODS: This was a cross-sectional observational, multicenter study. Patients diagnosed with AID and sJIA treated with canakinumab were included in the study. The participating 13 centers retrospectively collected their patients' data. RESULTS: A total of 335 patients were involved in the study. Among these patients, 280 were in the AID group and 55 were in the sJIA group. Canakinumab was administered at a median dose of 3 (2.5-4) mg/kg. The median total exposure time to canakinumab was 1.9 (0.8-3.2) years, corresponding to 759.5 patient-years. Seven hundred and seventy-nine total adverse events (AE) were identified. The total incidence of AE, and serious adverse events (SAE) throughout the study period was 1.02 per patient-years. The upper respiratory tract infection rate was 0.7 per patient-years, while the other infection rate was 0.13 per patient-years. While no death was observed in any patient, SAE were observed in 8 patients. Interstitial lung disease, anaphylaxis, or anaphylactoid reactions were not observed in any patient. CONCLUSIONS: Real-life data from a large cohort of patients suggests that canakinumab is as safe as claimed in clinical trials.

Do the features of juvenile psoriatic arthritis change according to age? A comprehensive evaluation of the PeRA Research Group Registry.

OBJECTIVES: To describe the clinical features and treatment outcomes of children with juvenile psoriatic arthritis (JPsA) and to compare the distinct patterns of the disease between early-onset and late-onset age groups. METHODS: Patients with JPsA followed regularly for at least 6 months between 2010-2020 in 7 pediatric rheumatology centers in Turkey were included in the study. The demographic features, clinical manifestations, treatment strategies, and outcomes of the patients were evaluated retrospectively. RESULTS: Eighty-seven (46 male/41 female) patients were included in the study. The mean age at diagnosis was 11.9 ± 4.5. Fifty-seven (65.5%) patients had psoriasis at the time of diagnosis, arthritis preceded psoriasis in 10 (11.5%) patients. Thirty (34.5%) patients had dactylitis, 28 (32.2%) had nail pitting, 36 (41.4%) had involvement of the small joints, 20 (23%) had enthesitis. Sacroiliitis was detected in 11 (12.6%) patients by magnetic resonance imaging. Anti-nuclear antibodies (ANA) were positive in 35 (40.2%) patients. Twelve children (%13.8) were in the early-onset (<5 years) group. Uveitis and ANA positivity were more common in the early-onset group. Active joint counts and activity scores of our patients showed significant improvement at 6th month and at the last control compared with baseline. CONCLUSION: About one-third of patients with JPsA do not have psoriasis at the time of diagnosis. In some patients, no skin lesion is seen during the course of the disease. Children with psoriatic arthritis seem to display two different phenotypes. Younger children have female predominance, ANA positivity, and uveitis, while older children have more axial involvement.

A pediatric case of Takayasu's arteritis with anti-neutrophil cytoplasmic antibody-associated vasculitis triggered by COVID-19 infection.

Takayasu's arteritis (TA) is a rare chronic granulomatous vasculitis characterized by large-vessel involvement. The aorta and its main branches are most commonly involved. Although pulmonary artery involvement is common, hemoptysis or respiratory findings are rarely seen. Herein, we present a case of TA who developed anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis with diffuse alveolar hemorrhage after coronavirus disease 2019 (COVID-19) infection. A 17-year-old female patient with the diagnosis of TA presented with cough, bloody vomiting, and diarrhea. In follow-up, she developed tachypnea and dyspnea and was transferred to the pediatric intensive care unit. The findings on the chest computed tomography were compatible with acute COVID-19 infection, but the SARS-CoV2 reverse transcription-polymerase chain reaction test was negative, but SARS-CoV2 immunoglobulin (Ig) G and IgM antibody tests were positive. The patient was not vaccinated against COVID-19. The bronchoscopy showed bronchial mucosal fragility, bleeding foci, and mucosal bleeding. The broncoalveolar lavage hemosiderin-laden macrophages were seen in the histopathologic examination. The indirect immunofluorescence assay-ANCA test became 3 (+) with myeloperoxidase (MPO)-ANCA of 125 RU/ml (normal: <20). Cyclophosphamide and pulse steroid treatment were started. After immunosuppressive therapy, the patient condition improved and did not have hemoptysis again. The successful response was obtained by applying balloon angioplasty to the patient with bilateral renal artery stenosis. Types of post-COVID vasculitis include thromboembolic events, cutaneous vasculitis, Kawasaki-like vasculitis, myopericarditis, and ANCA-associated vasculitis. It is thought that COVID-19 may impair immune tolerance and trigger autoimmunity with cross-reaction. To the best of our knowledge, the third pediatric case was reported with MPO-ANCA-positive COVID-associated ANCA vasculitis.

Not easy-peasy to diagnose: familial Mediterranean fever unaccompanied by fever.

Classical attacks of familial Mediterranean fever (FMF) are often accompanied by fever, but some of the patients have attacks without fever. This study aimed to compare the characteristics of FMF patients with and without fever during their attacks and draw attention to the different clinical presentations of FMF in children. Medical files of patients aged 0-18 years who were followed up with the diagnosis of FMF in two reference pediatric rheumatology centers were reviewed retrospectively. The patients were divided into two groups: children who had had no fever in any of their attacks were assigned as group 1, and those who had fever during their attacks were classified as group 2. Out of 2003 patients evaluated, 191 (9.53%) patients had attacks not accompanied by fever and their median age at onset of symptoms (7.0 vs. 4.0 years, p < 0.001) and the median age at diagnosis (8.6 vs. 6.0 years, p < 0.001) were significantly higher; however, group 2 had a delay in diagnosis. The annual number of attacks and abdominal attacks were more common in group 2; arthritis, arthralgia, erysipelas-like rash, exercise-induced leg pain, and myalgia were more common in group 1.    Conclusion: The data from the assessment of children with FMF attacks not accompanied with fever were presented for the first time. Children with late age onset of FMF and dominance of musculoskeletal features may display attacks not accompanied with fever. What is Known: • Familial Mediterranean fever (FMF) is the most common inherited auto-inflammatory disease, characterized by recurrent attacks of fever, serositis, and musculoskeletal symptoms. • Although fever is the most common symptom, few studies have reported attacks without fever. What is New: • The aim of this study was to identify patients with FMF but without fever during attacks and to demonstrate their distinctive presentations. • We found that 7% of our patients had afebrile attacks with predominant musculoskeletal symptoms and were diagnosed earlier than patients with febrile attacks, probably due to early referral to pediatric rheumatology clinics.

The assessment of autoinflammatory disease classification criteria (Eurofever/PRINTO) in a real-life cohort.

OBJECTIVE: The aim of the study was to determine the sensitivity and specificity rates of Eurofever/PRINTO autoinflammatory recurrent fever classification criteria with real-life data in patients with an autoinflammatory disease. METHODS: A total of 119 patients were included in the study. Based on clinical symptoms, they were divided into four subgroups: cryopyrin-associated periodic syndromes (CAPS), TNF receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency (MKD), and syndrome of undifferentiated recurrent fever (SURF) using the Eurofever/PRINTO clinical classification criteria. In the last step, the patients were re-evaluated in the light of genetic results and their final diagnosis was reached. RESULTS: A total of 119 patients, including 37 CAPS, 13 TRAPS, 8 MKD, 39 SURF, 14 NLRP12-related autoinflammatory disease (NLRP12-AID), and 8 familial Mediterranean fever (FMF) patients were evaluated in the study. While the sensitivity of the new clinical Eurofever/PRINTO criteria was 48% for CAPS, 77% for TRAPS, 87.5%for MKD, and the specificity of the clinical criteria was 86% for CAPS, 85% for TRAPS, and 60% for MKD. The sensitivity of the new mixed (genetic plus clinical variables) Eurofever/PRINTO criteria was 27% for CAPS, 61% forTRAPS, 85% for MKD, and the specificity of the mixed criteria for each group was 100%. CONCLUSION: We found the sensitivity of the Eurofever/PRINTO classification criteria to be low as genotypic changes between populations cause phenotypic differences. For this reason, we think that patient-based evaluation is correct rather than standard classification criteria in real life. Key-points • In systemic autoinflammatory diseases, common variants in the populations may alter the phenotype, and making it difficult to classify some patients with the current classification criteria. • In populations with common genetic variants, the classification criteria should be modified according to the clinical phenotype.

[Analysis of IFN-γR1 (CD119) and IL-12Rß1 (CD212) Deficiency by Flow Cytometry]. / IFN-γR1 (CD119) ve IL-12Rß1 (CD212) Eksikliginin Akan Hücre Ölçer ile Analizi.

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare primary immune deficiency (PID). IL-12Rß1 deficiency is the most frequently observed of more than 16 genetic defects that have been identified for MSMD. Genetic and immunological tests are remarkable in the diagnosis of PID. In this study, it was aimed to determine the expression of IFN-γR1 and IL-12Rß1 in patients with MSMD, their relatives, and healthy individuals and to evaluate the importance of flow cytometry as a fast and reliable method in the diagnosis of MSMD. IFN-γR1 and IL-12Rß1 expression levels were analyzed in 32 volunteers including six patients, six relatives, and 20 healthy individuals. The normal range of IFN-γR1 and IL-12Rß1 levels among healthy individuals were determined. IL-12Rß1 expression level in lymphocytes was found to be low in one patient's relative, and less than 1% in three patients and in one patient's relative. It was observed that the IL-12Rß1 expression levels of the patient with STAT1 deficiency were increased compared to the healthy individuals. No difference was found in the expression levels of IFN-γR1 and IL-12Rß1 in one patient, but IFN-γR1 expression was decreased in one patient compared to healthy individuals. Our results show that the determination of IL-12Rß1 and IFN-γR1 deficiencies by flow cytometry can be used as a rapid and reliable method for the diagnosis of MSMD. The use of this method as a screening test will enable early diagnosis especially in patients whose genetic diagnosis has not been confirmed and clinically compatible with MSMD. In addition, it is thought that IL-12Rß1 and IFN-γR1 range data obtained from healthy individuals will be considered as a reference source in routine and research studies to be conducted with MSMD.

PREDICT-crFMF score: A novel model for predicting colchicine resistance in children with familial Mediterranean fever.

OBJECTIVES: To develop a novel scoring system to predict colchicine resistance in Familial Mediterranean fever (FMF) based on the initial features of the patients. METHODS: The medical records of patients were analyzed prior to the initiation of colchicine. After generating a predictive score in the initial cohort, it was applied to an independent cohort for external validation of effectiveness and reliability. RESULTS: Among 1418 patients with FMF, 56 (3.9%) were colchicine resistant (cr) and 1312 (96.1%) were colchicine responsive. Recurrent arthritis (4 points), protracted febrile myalgia (8 points), erysipelas-like erythema (2 points), exertional leg pain (2 points), and carrying M694V homozygous mutation (4 points) were determined as the parameters for predicting cr-FMF in the logistic regression model. The cut-off value of 9 was 87% sensitive and 82% specific to foresee the risk of cr-FMF in the receiver operating characteristic. Validation of the scoring system with an independent group (cr-FMF = 107, colchicine responsive = 1935) revealed that the cut-off value was 82% sensitive and 79% specific to identify the risk of cr-FMF. CONCLUSIONS: By constructing this reliable and predictor tool, we enunciate that predicting cr-FMF at the initiation of the disease and interfering timely before the emergence of complications will be possible.

Cluster analysis of paediatric Behçet's disease: Data from The Pediatric Rheumatology Academy-Research Group.

OBJECTIVES: Behçet's disease (BD) is a systemic vasculitis affecting many organ systems, with the involvement of all-sized arteries and veins. The study aims to determine the main characteristics of paediatric BD patients and also analyse the clustering phenotypes. METHODS: Demographic data, clinical manifestations, laboratory features, treatment schedules, and disease outcomes were achieved from patients' charts retrospectively. A cluster analysis was performed according to the phenotype. RESULTS: A total of 225 (109 male/116 female) patients with BD were enrolled in the study. The median ages of disease onset and diagnosis were 131 (36-151) and 156 (36-192) months, respectively. According to cluster analysis, 132 (58.6%) patients belonged to the mucocutaneous-only cluster (C1), while 35 (15.6%) patients fitted to articular type (C2), 25 (11.1%) were in the ocular cluster (C3), 26 (11.6%) were in the vascular cluster (C4), and 7(3.1%) belonged to the gastrointestinal cluster (C5). Ocular and vascular clusters were more common in boys (p < .001), while girls usually presented with the mucocutaneous-only cluster. The disease activity at the diagnosis and the last control was higher in ocular, vascular, and gastrointestinal clusters. CONCLUSIONS: These identified juvenile BD clusters express different phenotypes with different outcomes Our analysis may help clinicians to identify the disease subtypes accurately and to arrange personalized treatment.

Real-life data on efficacy and safety of original Adalimumab and biosimilar Adalimumab (ABP 501) in pediatric rheumatic diseases.

BACKGROUND: We aimed to compare the efficacy and safety of the original product (OP) and biosimilar product (BP) of adalimumab in pediatric rheumatic diseases. RESEARCH DESIGN AND METHODS: The study group consisted of patients who had received original or biosimilar adalimumab (ABP 501) therapy for at least 3 months. The patients were divided into uveitis and arthritis groups based on the indication of adalimumab treatment. Assessment of disease activity was performed by Juvenile Arthritis Disease Activity Score in patients with juvenile idiopathic arthritis, and by standardization of uveitis nomenclature criteria in patients with uveitis. RESULTS: The study included 140 patients, of which 87 were treated with OP and 53 with BP. In the arthritis group, 26 (63.4%) and 20 (57.1%) patients reached inactive disease according to JADAS-27 in the original and biosimilar adalimumab groups, respectively. In the uveitis group the mean number of exacerbations throughout the treatment period was 0.84 ± 1.07 in the OP group, and 0.58 ± 0.79 in the BP group. There were 71 treatment-emergent adverse events in the OP group and 38 in the BP group. CONCLUSION: There was no significant difference between the biosimilar and the original product in efficacy and safety.

Differences and similarities of multisystem inflammatory syndrome in children, Kawasaki disease and macrophage activating syndrome due to systemic juvenile idiopathic arthritis: a comparative study.

To compare the clinical and laboratory findings of multisystem inflammatory syndrome in children (MIS-C), patients with Kawasaki disease (KD) and with macrophage activating syndrome due to systemic juvenile idiopathic arthritis (sJIA-MAS) on real-life data. Patients diagnosed with MIS-C, KD, and sJIA-MAS from 12 different centers in Turkey who were followed for at least 6 months were included in the study. Demographic, clinical, and laboratory findings of all patients were analyzed. A total of 154 MIS-C, 59 KD, and 31 sJIA-MAS patients were included. The median age of patients with MIS-C were higher than those with KD while lower than those with sJIA-MAS (8.2, 3, 12 years, respectively). Myalgia (39.6%), cardiac (50.6%), gastrointestinal (72.7%), and neurological (22.1%) involvements were more common in patients with MIS-C compared to others. MIS-C patients had lower levels of lymphocyte (950 vs 1700 cells/µl) and thrombocyte (173,000 vs 355,000 cells/µl) counts and higher pro-BNP (1108 vs 55 pg/ml) levels than KD. Ferritin levels were higher in patients with MIS-C compared to patients with KD while they were lower than patients with sJIA-MAS (440, 170, 10,442 ng/ml, respectively). Patients with MIS-C had a shorter duration of hospitalization than sJIA-MAS (p = 0.02) while they required intensive care unit admission more frequently (55 vs 8 patients, p < 0.001). The median MAS/sJIA score of MIS-C patients was - 1.64 (- 5.23 to 9.68) and the median MAS/sJIA score of sJIA-MAS patients was -2.81 ([- 3.79] to [- 1.27]). MIS-C patients displayed certain differences in clinical and laboratory features when compared to KD and sJIA-MAS. Definition of the differences and similarities between MIS-C and the other intense inflammatory syndromes of childhood such as KD and MAS will help the clinicians while making timely diagnosis.

The clinical course and short-term health outcomes of multisystem inflammatory syndrome in children in the single pediatric rheumatology center.

OBJECTIVES: Multisystem inflammatory syndrome in children (MIS-C) is a rare but severe condition resulting in excessive response of the immune system after SARS-CoV-2 infection. We report a single-center cohort of children with MIS-C, describing the spectrum of presentation, therapies, clinical course, and short-term outcomes. METHODS: This is a prospective observational study from to a tertiary pediatric rheumatology center including patients (aged 1 month to 21 years) diagnosed with MIS-C between April 2020-April 2021. Demographic, clinical, laboratory results and follow-up data were collected through the electronic patient record system and analyzed. RESULTS: A total of 67 patients with MIS-C were included in the study. Fever was detected in all patients; gastrointestinal system symptoms were found in 67.2% of the patients, rash in 38.8%, conjunctivitis in 31.3%, hypotension in 26.9% myocarditis, and/or pericarditis in 22.4%, respectively. Respiratory symptoms were only in five patients (7.5%). Kawasaki Disease like presentation was found 37.3% of the patients. The mean duration of hospitalization was 11.8 7.07 days. Fifty-seven patients (85%) received intravenous immunoglobulin (IVIG), 45 (67%) received corticosteroids, 17 (25.3%) received anakinra, and one (1.5%) received tocilizumab. Seven of the patients (10.4%) underwent therapeutic plasma exchange (TPE). In 21 (31.3%) patients, a pediatric intensive care unit (PICU) was required in a median of 2 days. The first finding to improve was fever, while the first parameter to decrease was ferritin (median 6.5 days (IQR, 4-11.2 days)). Sixty-five patients were discharged home with a median duration of hospital stay of 10 days (IQR, 7-15 days). CONCLUSION: Patients with MIS-C may have severe cardiac findings and intensive care requirements in admission and hospital follow-up. The vast majority of these findings improve with effective treatment without any sequelae until discharge and in a short time in follow-up. Although the pathogenesis and treatment plan of the disease are partially elucidated, follow-up studies are needed in terms of long-term prognosis and relapse probabilities.

Real-Life Data From the Largest Pediatric Familial Mediterranean Fever Cohort.

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease manifesting phenotypic heterogeneity. It is a clinically diagnosed disease supported by MEditerranean FeVer (MEFV) gene mutation analysis. However, the phenotype-genotype correlation is not yet established clearly. We aimed to determine the clinical findings, phenotype-genotype correlation, and treatment outcomes within a large pediatric FMF cohort. The medical charts of children with FMF who were diagnosed and followed up at the eight pediatric rheumatology units were reviewed retrospectively. All patients in the cohort were analyzed for sequence variants in exon 2,3,5 and 10 of the MEFV gene. Patients without any mutations or with polymorphisms including R202Q were excluded. A total of 3,454 children were involved in the study. The mean ± standard deviation of current age, age at symptom onset, and age at diagnosis were 12.1 ± 5.2, 5.1 ± 3.8, and 7.3 ± 4.0 years, respectively. Of 3,454 patients, 88.2% had abdominal pain, 86.7% had fever, 27.7% had arthritis, 20.2% had chest pain, 23% had myalgia, and 13.1% had erysipelas-like erythema. The most common MEFV mutation patterns were homozygous (32.5%) and heterozygous (29.9%) mutations of exon 10. Homozygous M694V was present in 969 patients (28.1%). Allele frequencies of common mutations were M694V (55.3%), M680I (11.3%), V726A (7.6%), and E148Q (7.2%). Children carrying homozygous or compound heterozygous exon 10 mutations had an earlier age of disease onset (4.6 vs. 5.6 years, p = 0.000) and a higher number of attacks per year (11.1 vs. 9.6, p = 0.001). Although 8% of the patients had a family history of amyloidosis, 0.3% (n = 11) had the presence of amyloidosis. M694V homozygosity was detected in nine patients who developed amyloidosis. Colchicine resistance was present in 4.2% of our patients. In this largest pediatric cohort reviewed and presented to date, patients with exon 10 mutations, particularly the M694V homozygous mutation, have been demonstrated earlier disease onset, annual attack count, and more frequent colchicine-resistant cases. Although E148Q is considered as a polymorphism in some populations, it was identified as a disease-causing mutation in our cohort. Secondary amyloidosis is still happening in adults however, it is extremely rare among children, presumably due to increased awareness, tight control, and the availability of anti-IL1 agents in colchicine-resistant cases.