3D clustering of gene expression data from systemic autoinflammatory diseases using self-organizing maps (Clust3D).

Background and objective: Systemic autoinflammatory diseases (SAIDs) are characterized by widespread inflammation, but for most of them there is a lack of specific biomarkers for accurate diagnosis. Although a number of machine learning algorithms have been used to analyze SAID datasets, aiding in the discovery of novel biomarkers, there is a growing recognition of the importance of SAID timeseries clustering, as it can capture the temporal dynamics of gene expression patterns. Methodology: This paper proposes a novel clustering methodology to efficiently associate three-dimensional data. The algorithm utilizes competitive learning to create a self-organizing neural network and adjust neuron positions in time-dependent and high dimensional feature space in order to assign them as clustering centers. The quantitative evaluation of the clustering was based on well-known clustering indices. Furthermore, a differential expression analysis and classification pipeline was employed to assess the capability of the proposed methodology to extract more accurate pathway-specific genes from its clusters. For that, a comparative analysis was also conducted against a heuristic timeseries clustering method. Results: The proposed methodology achieved better overall clustering indices scores and classification metrics using genes derived from its clusters. Notable cases include a threefold increase in the Calinski-Harabasz clustering index, a twofold improvement in the Davies-Bouldin clustering index and a ∼60% increase in the classification specificity score. Conclusion: A novel clustering methodology was developed and applied on several gene expression timeseries datasets from systemic autoinflammatory diseases, and its ability to efficiently produce well separated clusters compared to existing heuristic methods was demonstrated.

Identifying functional dysregulation of NOD2 variant Q902K in patients with Yao syndrome.

BACKGROUND AND OBJECTIVES: The study investigated the pathogenesis of Yao syndrome (YAOS), a rare systemic autoinflammatory disease associated with the nucleotide-binding oligomerization domain containing 2 (NOD2) gene variants. METHODS: RNA sequencing analyses were used to detect transcriptomic profile changes. Immunoblot and immunohistochemistry were used to examine the NOD2-mediated inflammatory signaling pathways and ELISA was used to detect cytokines. RESULTS: Transcriptome analysis of YAOS revealed NOD-like receptor signaling pathway enrichment. Compared with HCs, P-RIP2, p-p65, p-p38, p-ERK, and p-JNK notably increased in PBMCs of a patient with YAOS. P-RIP2, p-p65, and p-p38 elevated in small intestinal mucosa tissues. P-p65 and p-p38 in synovial tissues from YAOS were higher than those in patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Serum interleukin (IL)-6 level along with tumor necrosis factor (TNF)-α and IL-6 secreted from PBMCs were markedly higher in patients with YAOS in comparison to healthy controls (HCs). The supernatants of synovial cells from a patient with YAOS showed substantially higher IL-1ß and IL-6 levels than those of RA and OA. Canakinumab therapy of a Q902K heterozygous patient with YAOS resulted in notable clinical improvement. CONCLUSION: Overproduction of pro-inflammatory cytokines and the hyperactivation of NOD2-mediated signaling pathways were found in the NOD2 variant Q902K patient with YAOS. NOD2-RIP2-MAPK pathway might play a pivotal role in the pathogenesis of YAOS. These results provide new perspectives for targeted therapies in YAOS.

Cellular models in autoinflammatory disease research.

Systemic autoinflammatory diseases are a heterogeneous group of rare genetic disorders caused by dysregulation of the innate immune system. Understanding the complex mechanisms underlying these conditions is critical for developing effective treatments. Cellular models are essential for identifying new conditions and studying their pathogenesis. Traditionally, these studies have used primary cells and cell lines of disease-relevant cell types, although newer induced pluripotent stem cell (iPSC)-based models might have unique advantages. In this review, we discuss the three cellular models used in autoinflammatory disease research, their strengths and weaknesses, and their applications to inform future research in the field.

Identification of FDA-approved drugs that increase mevalonate kinase in hyper IgD syndrome.

Mevalonate kinase deficiency (MKD) is an autoinflammatory metabolic disorder caused by bi-allelic loss-of-function variants in the MVK gene, resulting in decreased activity of the encoded mevalonate kinase (MK). Clinical presentation ranges from the severe early-lethal mevalonic aciduria to the milder hyper-IgD syndrome (MKD-HIDS), and is in the majority of patients associated with recurrent inflammatory episodes with often unclear cause. Previous studies with MKD-HIDS patient cells indicated that increased temperature, as caused by fever during an inflammatory episode, lowers the residual MK activity, which causes a temporary shortage of non-sterol isoprenoids that promotes the further development of inflammation. Because an increase of the residual MK activity is expected to make MKD-HIDS patients less sensitive to developing inflammatory episodes, we established a cell-based screen that can be used to identify compounds and/or therapeutic targets that promote this increase. Using a reporter HeLa cell line that stably expresses the most common MKD-HIDS variant, MK-V377I, C-terminally tagged with bioluminescent NanoLuc luciferase (nLuc), we screened the Prestwick Chemical Library®, which includes 1280 FDA-approved compounds. Multiple compounds increased MK-V377I-nLuc bioluminescence, including steroids (i.e., glucocorticoids, estrogens, and progestogens), statins and antineoplastic drugs. The glucocorticoids increased MK-V377I-nLuc bioluminescence through glucocorticoid receptor signaling. Subsequent studies in MKD-HIDS patient cells showed that the potent glucocorticoid clobetasol propionate increases gene transcription of MVK and other genes regulated by the transcription factor sterol regulatory element-binding protein 2 (SREBP-2). Our results suggest that increasing the flux through the isoprenoid biosynthesis pathway by targeting the glucocorticoid receptor or SREBP-2 could be a potential therapeutic strategy in MKD-HIDS.

Anti-Interleukin-1 Therapy Does Not Affect the Response to SARS-CoV-2 Vaccination and Infection in Patients with Systemic Autoinflammatory Diseases.

Patients with systemic autoinflammatory diseases (sAIDs) are a section of the population at high risk of severe COVID-19 outcomes, but evidence on the efficacy of SARS-CoV-2 vaccination in this group of patients is scarce. To investigate the efficacy of SARS-CoV-2 vaccination in patients with sAIDs receiving interleukin-1 (IL-1) inhibition is important. Vaccination and infection responses from 100 sAID patients and 100 healthy controls (HCs) were analyzed. In total, 98% of patients were treated with IL-1 inhibitors at the time of vaccination (n = 98). After the second SARS-CoV-2 vaccination, sAID patients showed similar anti-SARS-CoV-2 antibody responses (mean (standard deviation (SD)): 6.7 (2.7)) compared to HCs (5.7 (2.4)) as well as similar neutralizing antibodies (85.1 ± 22.9% vs. 82.5 ± 19.7%). Anti-SARS-CoV-2 antibody responses and neutralizing antibodies were similar in sAID patients after SARS-CoV-2 infection and double vaccination. Furthermore, while antibodies increased after the first and second vaccination in sAID patients, they did not further increase after the third and fourth vaccination. No difference was found in antibody responses between anakinra and anti-IL-1 antibody treatment and the additional use of colchicine or other drugs did not impair vaccination responses. Primary and booster SARS-CoV-2 vaccinations led to protective antibody responses in sAID patients, which were at the same level of vaccination responses in HCs and in sAID patients after SARS-CoV-2 infection. Immunomodulatory treatments used in sAID do not seem to affect antibody responses to the SARS-CoV-2 vaccine.

How to Build a Fire: The Genetics of Autoinflammatory Diseases.

Systemic autoinflammatory diseases (SAIDs) are a heterogeneous group of disorders caused by excess activation of the innate immune system in an antigen-independent manner. Starting with the discovery of the causal gene for familial Mediterranean fever, more than 50 monogenic SAIDs have been described. These discoveries, paired with advances in immunology and genomics, have allowed our understanding of these diseases to improve drastically in the last decade. The genetic causes of SAIDs are complex and include both germline and somatic pathogenic variants that affect various inflammatory signaling pathways. We provide an overview of the acquired SAIDs from a genetic perspective and summarize the clinical phenotypes and mechanism(s) of inflammation, aiming to provide a comprehensive understanding of the pathogenesis of autoinflammatory diseases.

Enfermedades autoinflamatorias sistémicas, entidades en auge: generalidades, principales síndromes monogénicos y aproximación al manejo terapéutico / Systemic autoinflammatory diseases, entities on the rise: basic concepts, main monogenic syndromes and approach to therapeutic management

Systemic autoinflammatory diseases are relatively recent entities caused by dysregulation of the innate immune system. They are mainly caused by monogenic mutations, although there are entities produced by polygenic mutations or of multifactorial origin. Traditionally, they have been classified based on the presence or absence of fever, however, thanks to the advancement of knowledge of their Pathogenic mechanisms and the signaling pathways involved, recently it has been advocated to classify them based on the latter. The three more important groups of monogenic autoinflammatory diseases are type 1 interferonopathies, inflammasomopathies and dysregulation in the nuclear factor kappa light chain enhancer of activated B cells [NFkB] pathway (relopahies). In this review, the main pathways involved, the main syndromes of each of these groups and the therapeutic approach are addressed. (AU)

Las enfermedades autoinflamatorias sistémicas son entidades relativamente recientes ocasionadas por disregulación del sistema inmune innato. Están ocasionadas fundamentalmente por mutaciones monogénicas, aunque existen entidades producidas por mutaciones poligénicas o de origen multifactorial. Tradicionalmente se han clasificadoen función de la presencia o ausencia de fiebre, sin embargo, con el avance en el conocimiento de sus mecanismos patogénicos y de las vías de señalización involucradas, recientemente se aboga por clasificarlas en base a esto último, siendo los tres grupos más importantes de entidades autoinflamatorias monogénicas las interferonopatías tipo 1,las inflamasomopatías y las ocasionadas por disregulación en la vía del factor nuclear potenciador de las cadenas ligeras kappa de las células B activadas [NF-KB] (relopatías). En la presente revisión se aborda de forma general las principales vías implicadas, los principales síndromes de cada uno de estos grupos y el abordaje terapéutico. (AU)

[Role of interleukin-1 in human diseases: pharmacotherapy prospects: A review].

According to current concepts, human immunoinflammatory diseases (IIDs), depending on the prevailing mechanisms of immunopathogenesis, are divided into two main categories: autoimmune and autoinflammatory. At the same time, both autoimmune and autoinflammatory mechanisms are involved in the pathogenesis of most IIDs, and the complex interaction of these mechanisms is reflected in the polymorphism of clinical presentation, course variants, outcomes and therapy efficacy. It is suggested that in IIDs, overproduction of cytokines of the interleukin (IL)-1 family, which is one of the key regulators of innate immunity, determines the "crossing" between autoinflammation and autoimmunity mechanisms. Currently, anakinra, a recombinant non-glycosylated analog of the IL-1 receptor antagonist that blocks both IL-1b and IL-1a signaling, and canakinumab, a monoclonal antibody to IL-1b, are used in clinical practice to inhibit the pathological effects of IL-1. Analysis of the treatment outcomes with these drugs suggests that IL-1 inhibition should be considered a promising direction of pharmacotherapy of systemic autoinflammatory diseases and critical conditions associated with hyperinflammation in children and adults.

Immune-mediated inflammatory diseases with chronic excess of serum interleukin-18.

Review: Interleukin-18 (IL-18) is a proinflammatory cytokine that promotes various innate immune processes related to infection, inflammation, and autoimmunity. Patients with systemic juvenile idiopathic arthritis and adult-onset Still's disease exhibit chronic excess of serum IL-18, which is associated with a high incidence of macrophage activation syndrome (MAS), although the mechanisms of IL-18 regulation in such diseases remain largely unknown. Similar elevation of serum IL-18 and susceptibility to MAS/hemophagocytic lymphohistiocytosis (HLH) have been reported in monogenic diseases such as X-linked inhibitor of apoptosis deficiency (i.e., X-linked lymphoproliferative syndrome type 2) and NLRC4-associated autoinflammatory disease. Recent advances in molecular and cellular biology allow the identification of other genetic defects such as defects in CDC42, PSTPIP1, and WDR1 that result in high serum IL-18 levels and hyperinflammation. Among these diseases, chronic excess of serum IL-18 appears to be linked with severe hyperinflammation and/or predisposition to MAS/HLH. In this review, we focus on recent findings in inflammatory diseases associated with and probably attributable to chronic excess of serum IL-18 and describe the clinical and therapeutical relevance of understanding the pathology of this group of diseases.

NLRP12-associated systemic autoinflammatory diseases in children.

Systemic autoinflammatory diseases (SAIDs) are a group of monogenic diseases characterized by disordered innate immunity, which causes excessive activation of inflammatory pathways. Nucleotide-binding leucine-rich repeat-containing receptor 12-related autoinflammatory disease (NLRP12-AID) is a newly identified SAID and a rare autosomal dominant disorder caused by mutations in the NLRP12 gene, which is also known as familial cold autoinflammatory syndrome 2 (FCAS2) and mostly occurs in childhood. A total of 33 cases of NLRP12-AID in children and 21 different mutation types have been reported to date. The disease is mainly characterized by periodic fever, accompanied by multisystem inflammatory damage. NLRP12-AID is diagnosed through early clinical identification and genetic detection. Emerging drugs targeting interleukin-1-related inflammatory pathways are expected to change the treatment options and improve the quality of life of pediatric patients. This article aims to summarize the characteristics and pathogenesis of reported NLRP12-AID cases in children and provide ideas for clinical diagnosis and treatment.

COVID-19 and autoinflammatory diseases: prevalence and outcomes of infection and early experience of vaccination in patients on biologics.

OBJECTIVES: The systemic autoinflammatory diseases are rare conditions; to date, data on coronavirus disease 2019 (COVID-19) infection and vaccination safety are scarce. Agents targeting innate immune pathways have transformed the management of affected patients, and their outcomes are of wider interest given the role of inflammation in both viral clearance and severe COVID-19 disease. We surveyed patients with systemic autoinflammatory disease on biologic therapy to determine the prevalence and outcomes of COVID-19 infection and to gather early safety data on vaccination. METHODS: Electronic medical records of 248 patients with systemic autoinflammatory disease on biologic therapy at a national centre were reviewed. Patients were then surveyed in clinic or using a Web-based survey. RESULTS: In the cohort of 248 patients, no deaths were recorded. One hundred and seventy-five survey responses were received. Among the respondents, 27 reported suspected COVID-19 infection, of which 14 were confirmed by testing (8.0%). Two patients required hospital admission owing to dehydration. No patient required respiratory support or intensive care. One hundred and thirty-eight doses of COVID-19 vaccine had been administered to 130 patients. Side effects were reported after 71 of 138 (51.4%) administrations and were consistent with a flare of the underlying disease in 26 of 138 (18.8%) instances. No serious adverse events or hospital admissions were reported after vaccination. CONCLUSION: These data, including the largest published series of patients on anti-IL-1/6 biologics to receive any adenoviral vector or messenger RNA vaccine, show no serious early concerns regarding vaccination and will provide an urgently needed resource to inform decision-making of these patients and their clinicians.

Monogenic Autoinflammatory Diseases: State of the Art and Future Perspectives.

Systemic autoinflammatory diseases are a heterogeneous family of disorders characterized by a dysregulation of the innate immune system, in which sterile inflammation primarily develops through antigen-independent hyperactivation of immune pathways. In most cases, they have a strong genetic background, with mutations in single genes involved in inflammation. Therefore, they can derive from different pathogenic mechanisms at any level, such as dysregulated inflammasome-mediated production of cytokines, intracellular stress, defective regulatory pathways, altered protein folding, enhanced NF-kappaB signalling, ubiquitination disorders, interferon pathway upregulation and complement activation. Since the discover of pathogenic mutations of the pyrin-encoding gene MEFV in Familial Mediterranean Fever, more than 50 monogenic autoinflammatory diseases have been discovered thanks to the advances in genetic sequencing: the advent of new genetic analysis techniques and the discovery of genes involved in autoinflammatory diseases have allowed a better understanding of the underlying innate immunologic pathways and pathogenetic mechanisms, thus opening new perspectives in targeted therapies. Moreover, this field of research has become of great interest, since more than a hundred clinical trials for autoinflammatory diseases are currently active or recently concluded, allowing us to hope for considerable acquisitions for the next few years. General paediatricians need to be aware of the importance of this group of diseases and they should consider autoinflammatory diseases in patients with clinical hallmarks, in order to guide further examinations and refer the patient to a specialist rheumatologist. Here we resume the pathogenesis, clinical aspects and diagnosis of the most important autoinflammatory diseases in children.

A computational workflow for the detection of candidate diagnostic biomarkers of Kawasaki disease using time-series gene expression data.

Unlike autoimmune diseases, there is no known constitutive and disease-defining biomarker for systemic autoinflammatory diseases (SAIDs). Kawasaki disease (KD) is one of the "undiagnosed" types of SAIDs whose pathogenic mechanism and gene mutation still remain unknown. To address this issue, we have developed a sequential computational workflow which clusters KD patients with similar gene expression profiles across the three different KD phases (Acute, Subacute and Convalescent) and utilizes the resulting clustermap to detect prominent genes that can be used as diagnostic biomarkers for KD. Self-Organizing Maps (SOMs) were employed to cluster patients with similar gene expressions across the three phases through inter-phase and intra-phase clustering. Then, false discovery rate (FDR)-based feature selection was applied to detect genes that significantly deviate across the per-phase clusters. Our results revealed five genes as candidate biomarkers for KD diagnosis, namely, the HLA-DQB1, HLA-DRA, ZBTB48, TNFRSF13C, and CASD1. To our knowledge, these five genes are reported for the first time in the literature. The impact of the discovered genes for KD diagnosis against the known ones was demonstrated by training boosting ensembles (AdaBoost and XGBoost) for KD classification on common platform and cross-platform datasets. The classifiers which were trained on the proposed genes from the common platform data yielded an average increase by 4.40% in accuracy, 5.52% in sensitivity, and 3.57% in specificity than the known genes in the Acute and Subacute phases, followed by a notable increase by 2.30% in accuracy, 2.20% in sensitivity, and 4.70% in specificity in the cross-platform analysis.

Clinical benefits of TNF-α inhibitors in Chinese adult patients with NLRP3-associated autoinflammatory disease.

BACKGROUND: Nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3)-associated autoinflammatory disease (NLRP3-AID) is a rare, heterogeneous disease entity associated with mutations in NLRP3. Biologic therapy for NLRP3-AID yields diverse results. OBJECTIVES: We aimed to evaluate the clinical features and outcomes of Chinese adult patients with NLRP3-AID who were treated with tumour necrosis factor (TNF)-α inhibitors. METHODS: Five patients with NLRP3-AID were diagnosed and treated with TNF-α inhibitors at Peking Union Medical College Hospital between 2017 and 2020 and were followed up for 6 to 12 months. All patients were systematically studied for treatment outcomes, including clinical manifestations and inflammatory markers. RESULTS: All five adult NLRP3-AID patients were Chinese Han, and four patients were males. The mean age at disease onset was 4.2 ± 4.1 years, and the mean time of diagnosis delay was 19.8 ± 6 years. All patients received TNF-α inhibitors with or without methotrexate/prednisone. During follow-up, all patients achieved remarkable clinical remission of skin lesions and polyarthritis and showed improvements in acute-phase reactants, inflammatory cytokines, patient visual analogue scale, physician global assessment and 36-item Short Form (SF-36). CONCLUSIONS: Early diagnosis and effective therapy for NLRP3-AID are essential for avoiding irreversible organ damage. TNF-α inhibitors might serve as a therapeutic alternative for patients with NLRP3-AID who have unsatisfactory responses or no access to interleukin-1 inhibitors.

Suboptimal vaccination coverage of recommended vaccines among French children with recurrent autoinflammatory fever syndromes: a study from the Juvenile Inflammatory Rheumatism cohort.

INTRODUCTION/OBJECTIVES: To determine vaccination coverage among a French cohort of children with recurrent autoinflammatory fever syndromes (RFS). METHOD: All RFS children aged 2 to 19 years from the Juvenile Inflammatory Rheumatism cohort and followed at the French Reference Center for Autoinflammatory Diseases, Versailles Hospital, were included in our observational study. Immunisation status at ages 2, 7 and 15 years and at the last outpatient visit was evaluated according to the standard French vaccine schedule and recommended supplementary vaccines for patients with immunosuppressive therapy. RESULTS: Of 200 patients, 90 (45%) had periodic fever, aphthous stomatitis, pharyngitis and adenitis syndrome; 52 (26%) had familial Mediterranean fever and 50 (25%) had undefined recurrent fever. Complete immunisation as per the standard schedule was obtained by 32% of patients at 2 years, 28% at 7 years, 6% at 15 years and 44% at the last outpatient visit. Similar or higher coverage was obtained by the last outpatient visit for most vaccines, compared to immunisation coverage at 2 years: pneumococcus (91% vs 88%), diphtheria tetanus poliomyelitis (82% vs 86%), hepatitis B (79% vs 69%) and measles, mumps, rubella (91% vs 50%). No patients with immunosuppressive therapy (n = 14) were up to date for all supplementary immunisations recommended for them. CONCLUSION: Vaccination coverage for RFS children is suboptimal, especially for infants who present with recurrent febrile episodes. The initial vaccination delay is partially corrected through specialist follow-up in later years. Coverage according to the supplementary vaccine recommendations for immunosuppressed patients is poor. Key Points • Vaccination coverage for RFS children is suboptimal, especially at 2 years of age which is likely due to the prevalence of early recurrent febrile symptoms. • The initial vaccination delay is partially recovered during later follow-up at an expert rheumatology center. • Specific recommendations are particularly difficult to apply to patients on immunosuppressive therapy.

Comparison of the clinical diagnostic criteria and the results of the next-generation sequence gene panel in patients with monogenic systemic autoinflammatory diseases.

INTRODUCTION/OBJECTIVES: The clinicians initially prefer to define patients with the systemic autoinflammatory disease (SAID)'s based on recommended clinical classification criteria; then, they confirm the diagnosis with genetic testing. We aimed to compare the initial phenotypic diagnoses of the patients who were followed up with the preliminary diagnosis of a monogenic SAID, and the genotypic results obtained from the next-generation sequence (NGS) panel. METHOD: Seventy-one patients with the preliminary diagnosis of cryopyrin-associated periodic fever syndrome (CAPS), mevalonate kinase deficiency (MKD), or tumor necrosis factor-alpha receptor-associated periodic fever syndrome (TRAPS) were included in the study. The demographic data, clinical findings, laboratory results, and treatments were recorded. All patients were examined by NGS panel analysis including 16 genes. The genetic results were compared with the initial Federici score to determine whether they were compatible with each other. RESULTS: Thirty patients were initially classified as MKD, 22 as CAPS, and 19 as TRAPS. The frequency of clinical manifestations was urticarial rash 57.7%, diarrhea 49.2%, abdominal pain 47.8%, arthralgia 45%, oral aphthae 43.6%, myalgia 32.3%, tonsillitis 28.1%, and conjunctivitis 25.3%, respectively. After NGS gene panel screening, 13 patients were diagnosed with CAPS, 8 with MKD, 7 with familial Mediterranean fever, 5 with TRAPS, and 2 with NLRP12-associated periodic syndrome. The remaining 36 patients were genetically identified as undefined SAID since they were not classified as one of the defined SAIDs after the result of the NGS panel. CONCLUSIONS: We have demonstrated that clinical diagnostic criteria may not always be sufficient to establish the correct diagnosis. There is still low accordance between clinical diagnoses and molecular analyses. In the case of a patient with a preliminary diagnosis of a monogenic SAID with the negative result of target gene analysis, other autoinflammatory diseases should also be kept in mind in the differential diagnosis. Key Points • Monogenic autoinflammatory diseases can present with different clinical manifestations. • The clinical diagnostic criteria may not always be sufficient to reach the correct diagnosis in autoinflammatory diseases. • In the case of a patient with a preliminary diagnosis of a monogenic SAID with the negative result of target gene analysis, other autoinflammatory diseases should be kept in mind in the differential diagnosis.

Systemic autoinflammatory diseases: Clinical state of the art.

Systemic autoinflammatory diseases (SAIDs) are defined as disorders of innate immunity. They were initially defined in opposition to autoimmune diseases due to the lack of involvement of the adaptive immune system and circulating autoantibodies. The four historical monogenic diseases are familial Mediterranean fever (associated with MEFV mutations), cryopyrinopathies (NLRP3 mutations), tumor necrosis factor receptor-associated periodic syndrome (TNFRSF1A mutations), and mevalonate kinase deficiency (MVK mutations). In the last 10 years, more than 50 new monogenic SAIDs have been discovered thanks to advances in genetics. Diagnosis is largely based on personal and family history and detailed analysis of signs and symptoms associated with febrile attacks, in the setting of elevated inflammatory markers. Increasingly efficient techniques of genetic analysis can contribute to refining the diagnosis. This review is a guide for the clinician in suspecting and establishing a diagnosis of SAID.

Genetic panel screening in patients with clinically unclassified systemic autoinflammatory diseases.

OBJECTIVE: Systemic autoinflammatory diseases (SAIDs) may not always present with typical clinical findings of a monogenic disease. We aimed to genetically screen and diagnose these clinically unclassified patients by next-generation sequencing (NGS) analysis. METHOD: A total of 64 patients who had clinical findings of a periodic fever syndrome but did not meet the clinical diagnostic criteria for any SAID or had clinical findings for more than one monogenic SAID were identified as "clinically unclassified SAIDs." NGS panel analysis, including 16 genes, was performed in these patients. Patients, who could not be classified as one of the defined SAID after the result of the NGS gene analysis, were identified as "undefined SAID." RESULTS: The most common autoinflammatory symptoms in unclassified SAID patients were abdominal pain (60.9%), arthralgia (48.4%), urticarial rash (43.8%), myalgia (40.6%), oral aphthae (28.1%), and conjunctivitis (20.3%), respectively. In the result of the NGS gene panel screening, pathogenic, likely pathogenic variants, or VUS (variants of uncertain significance) were detected in 36 of 64 patients in at least one gene in the NGS panel. A total of 15 patients were diagnosed with a monogenic SAID according to both phenotypic and genotypic data; 12 patients as FMF, two patients as FCAS, and one patient as TRAPS, respectively. A total of 49 patients who did not meet the classification criteria including genetic results for a monogenic SAID were followed as undefined SAID. CONCLUSIONS: The classification criteria described for SAIDs so far unfortunately do not cover all patients with signs of periodic fevers. The NGS gene panel appears to be a useful diagnostic tool for some of the patients with clinically unclassified SAID findings. Key Points • The classification criteria described for SAIDs do not cover all patients with signs of periodic fevers • The use of the undefined SAID nomenclature will benefit clinicians for diagnosis and initiating early treatment • The NGS panel appears to be a useful diagnostic tool in patients with clinically unclassified SAIDs.

Next generation sequencing panel in undifferentiated autoinflammatory diseases identifies patients with colchicine-responder recurrent fevers.

OBJECTIVES: The number of innate immune system disorders classified as systemic autoinflammatory diseases (SAID) has increased in recent years. More than 70% of patients with clinical manifestations of SAID did not receive a molecular diagnosis, thus being classed as so-called undifferentiated or undefined SAID (uSAID). The aim of the present study was to evaluate a next-generation sequencing (NGS)-based clinically oriented protocol in patients with uSAID. METHODS: We designed a NGS panel that included 41 genes clustered in seven subpanels. Patients with uSAID were classified into different groups according to their clinical features and sequenced for the coding portions of the 41 genes. RESULTS: Fifty patients were enrolled in the study. Thirty-four patients (72%) displayed recurrent fevers not consistent with a PFAPA phenotype. Sixteen patients displayed a chronic inflammatory disease course. A total of 100 gene variants were found (mean 2 per patient; range 0-6), a quarter of which affected suspected genes. Mutations with a definitive diagnostic impact were detected in two patients. Patients with genetically negative recurrent fevers displayed a prevalent gastrointestinal, skin and articular involvement. Patients responded to steroids on demands (94%) and colchicine, with a response rate of 78%. CONCLUSION: Even with a low molecular diagnostic rate, a NGS-based approach is able to provide a final diagnosis in a proportion of uSAID patients with evident cost-effectiveness. It also allows the identification of a subgroup of genetically negative patients with recurrent fever responding to steroid on demand and colchicine.