New workflow for classification of genetic variants' pathogenicity applied to hereditary recurrent fevers by the International Study Group for Systemic Autoinflammatory Diseases (INSAID)

MEFV gene allele frequency and genotype distribution in 3230 patients' analyses by next generation sequencing methods

Familial Mediterranean Fever (FMF, OMIM ID: 249100) is the most common autoinflammatory, autosomal recessive disease caused by mutations in the MEFV gene. It is widespread in the Mediterranean, primarily among Turkish, Armenian, Arab and Jewish. This study aims to examine genotype distributions of common MEFV variants in the Turkish population using targeted NGS and to evaluate all rare mutations. It included 3230 people applying to Ege University Children's Hospital Molecular Medicine Laboratory with the suspicion of autoinflammatory disease between 2017 and 2021. MEFV missense variant was detected in 1839 (56.9%) individuals. One or more mutations were found in them. 1063 patients were heterozygous (57.8%), 410 were compound heterozygous (22.3%), 238 were complex genotype (12.9%), and 128 were homozygous (7%). 56 different mutations and 141 genotypes were detected, two of which were novel (p.His87Arg, c.260A > G and p.Leu396Phe, c.1186C > T). These were determined as 6benign, 40 uncertain significant, 3 likely pathogenic and 7 pathogenic according to the ACMG classification. The most common ones were R202Q (n = 1097, 37.48%), E148Q (n = 512, 17.49%), M694V (n = 493, 16.84%), V726A (n = 155, 5.30%), M680I (n = 150, 5.12%), P369S (n = 108, 3.69%), R408Q (n = 95, 3.25%) respectively. They constitute 89.17 % of the entire patient population. In conclusion, DNA variants/mutations in the MEFV gene were evaluated in 3230 patients. To date, no mutation screening has been encountered in such a large population using NGS. Genotype distributions of both common and rare mutations were revealed. The obtained data will hopefully contribute to the future genotype-phenotype studies of FMF disease.

Pericarditis and Autoinflammation: A Clinical and Genetic Analysis of Patients With Idiopathic Recurrent Pericarditis and Monogenic Autoinflammatory Diseases at a National Referral Center

Background Idiopathic recurrent pericarditis (IRP) is an orphan disease that carries significant morbidity, partly driven by corticosteroid dependence. Innate immune modulators, colchicine and anti-interleukin-1 agents, pioneered in monogenic autoinflammatory diseases, have demonstrated remarkable efficacy in trials, suggesting that autoinflammation may contribute to IRP. This study characterizes the phenotype of patients with IRP and monogenic autoinflammatory diseases, and establishes whether autoinflammatory disease genes are associated with IRP. Methods and Results We retrospectively analyzed the medical records of patients with IRP (n=136) and monogenic autoinflammatory diseases (n=1910) attending a national center (London, UK) between 2000 and 2021. We examined 4 genes (MEFV, MVK, NLRP3, TNFRSF1A) by next-generation sequencing in 128 patients with IRP and compared the frequency of rare deleterious variants to controls obtained from the Genome Aggregation Database. In this cohort of patients with IRP, corticosteroid dependence was common (39/136, 28.7%) and was associated with chronic pain (adjusted odds ratio 2.8 [95% CI, 1.3-6.5], P=0.012). IRP frequently manifested with systemic inflammation (raised C-reactive protein [121/136, 89.0%] and extrapericardial effusions [68/136, 50.0%]). Pericarditis was observed in all examined monogenic autoinflammatory diseases (0.4%-3.7% of cases). Rare deleterious MEFV variants were more frequent in IRP than in ancestry-matched controls (allele frequency 9/200 versus 2932/129 200, P=0.040). Conclusions Pericarditis is a feature of interleukin-1 driven monogenic autoinflammatory diseases and IRP is associated with variants in MEFV, a gene involved in interleukin-1β processing. We also found that corticosteroid dependence in IRP is associated with chronic noninflammatory pain. Together these data implicate autoinflammation in IRP and support reducing reliance on corticosteroids in its management.

Induced Pluripotent Stem Cell-Derived Monocytes/Macrophages in Autoinflammatory Diseases

The concept of autoinflammation, first proposed in 1999, refers to a seemingly unprovoked episode of sterile inflammation manifesting as unexplained fever, skin rashes, and arthralgia. Autoinflammatory diseases are caused mainly by hereditary abnormalities of innate immunity, without the production of autoantibodies or autoreactive T cells. The revolutionary discovery of induced pluripotent stem cells (iPSCs), whereby a patient’s somatic cells can be reprogrammed into an embryonic pluripotent state by forced expression of a defined set of transcription factors, has the transformative potential to enable in vitro disease modeling and drug candidate screening, as well as to provide a resource for cell replacement therapy. Recent reports demonstrate that recapitulating a disease phenotype in vitro is feasible for numerous monogenic diseases, including autoinflammatory diseases. In this review, we provide a comprehensive overview of current advances in research into autoinflammatory diseases involving iPSC-derived monocytes/macrophages. This review may aid in the planning of new studies of autoinflammatory diseases.

[Autoinflammation-A clinical and genetic challenge]

In the last two decades clinical rheumatological practice has been confronted with a steadily increasing number of autoinflammatory diseases, the immunological pathomechanisms of which have been elucidated and in part can be clinically well classified. Whereas targeted genetic diagnostics previously served to confirm a clinically suspected diagnosis, genetic sequencing technology has much improved and enables a new diagnostic approach via high-throughput sequencing, e.g., panel sequencing, whole exome and whole genome sequencing. Thus, the decision to make a diagnosis clinically and/or genetically, has become a daily challenge. This article contrasts the clinical, immunological and genetic aspects of autoinflammatory diseases.

The impact of the Eurofever criteria and the new InFevers MEFV classification in real life: Results from a large international FMF cohort

INTRODUCTION

New Eurofever/PRINTO classification criteria (EPCC) for Familial Mediterranean Fever (FMF) and other recurrent fevers have been recently developed, together with the classification of the pathogenicity of MEFV variants.

OBJECTIVES

To evaluate the impact in real life of both the EPCC and INSAID pathogenicity classification of MEFV variants in the large international Eurofever FMF cohort.

METHODS

Baseline demographic, genetic and clinical data of FMF patients included in the Eurofever registry were evaluated. The EPCC and the 2018 INSAID classification for MEFV variants were applied in all eligible FMF patients.

RESULTS

Since November 2009, clinical information was available for 1012 FMF (532 males/480 females, 827 children/185 adults) from 119 centres. Complete data were available for 887 patients in whom 623 (70.2%) satisfied EPCC (EPCC+), while 264 (29.8%) did not (EPCC-). The majority of the EPCC- patients (172, 65.1%) displayed negative or non-informative genetics (monoallelic or biallelic benign variants, monoallelic variant of unknown significance). At baseline, colchicine was used in most of EPCC+ patients (88%) and in a lower percentage of EPCC- patients (69%, p < 0.0001), who were treated in a higher proportion with steroid or NSAID on demand (p = 0.003 and 0.008, respectively). Four percent of patients received Anti-IL-1 treatment.

CONCLUSIONS

The combination of EPCC and the 2018 INSAID classification of MEFV variants is able to identify two distinct groups of patients, which differ in clinical characteristics, therapeutic approach and response to treatment. EPCC+ patients displayed the typical features of FMF, while EPCC- patients had a more variable phenotype with a lower percentage of response to colchicine.

The analysis of genotype-phenotype correlation in familial Mediterranean fever

BACKGROUND

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease manifesting with phenotypic heterogeneity. It is a clinically diagnosed disease supported by Mediterranean fever gene mutation analysis. This medical record review study aimed to make a new interpretation of clinical features in FMF patients by grouping genetic results based on the classification proposed by the Eurofever/ Paediatric Rheumatology International Trials Organisation.

METHODS

The medical charts of pediatric FMF patients who were diagnosed and followed up regularly at the two pediatric rheumatology units were reviewed. Genetic analysis results were classified as confirmatory and nonconfirmatory as defined in the new Eurofever/ Paediatric Rheumatology International Trials Organisation classification criteria, and they were compared with clinical findings.

RESULTS

A total of 216 FMF patients were involved in the study. Group 1 was composed of 133 (61.6%) patients with a confirmatory mutation and group 2 included 83 (38.4%) patients with a nonconfirmatory mutation. All clinical findings were compared, and in terms of fever (P = 0.027), abdominal pain (P = 0.016), arthritis (P = 0.008) and erysipelas-like erythema (ELE; P = 0.003) incidence, there was a significant difference between the two groups. The most common Mediterranean fever gene mutation patterns were homozygous (33.8%) and heterozygous (17.1%) mutations of M694V. The frequency of arthritis and ELE in patients with M694V homozygous mutations was significantly higher than in the other patients (P = 0.002 and P <0.001, respectively).

CONCLUSIONS

The most frequently observed clinical features of FMF (i.e., fever and abdominal pain) are both observed in patients with confirmatory and nonconfirmatory mutations, ELE and arthritis are more commonly observed in patients with confirmatory mutations.

Systemic Autoinflammatory Diseases: A Growing Family of Disorders of Overlapping Immune Dysfunction

Systemic autoinflammatory diseases (SAIDs) are characterized by unprovoked exaggerated inflammation on a continuum from benign recurrent oral ulceration to life-threatening strokes or amyloidosis, with renal failure as a potential sequela. The ability to discriminate these diagnoses rests on the genetic and mechanistic defect of each disorder, considering potential overlapping autoinflammation, autoimmunity, and immune deficiency. A comprehensive and strategic genetic investigation influences management as well as the consequential expected prognoses in these subsets of rare diseases. The ever-expanding therapeutic armamentarium reflects international collaborations, which will hasten genetic discovery and consensus-driven treatment.

Real-Life Indications of Interleukin-1 Blocking Agents in Hereditary Recurrent Fevers: Data From the JIRcohort and a Literature Review

Background

Interleukin (IL)-1 inhibitors represent the main treatment in patients with colchicine-resistant/intolerant familial Mediterranean fever (crFMF), mevalonate kinase deficiency (MKD), and tumor necrosis factor receptor-associated periodic syndrome (TRAPS). However, the reasons for the use of IL-1 inhibitors in these diseases are still not completely clarified.

Objective

Identify real-life situations that led to initiating anakinra or canakinumab treatment in hereditary recurrent fevers (HRFs), combining data from an international registry and an up-to-date literature review.

Patients and Methods

Data were extracted from the JIRcohort, in which clinical information (demographic data, treatment, disease activity, and quality of life) on patients with FMF, MKD, and TRAPS was retrospectively collected. A literature search was conducted using Medline, EMBASE, and Cochrane databases.

Results

Complete data of 93 patients with HRF (53.8% FMF, 31.2% MKD, and 15.1% TRAPS) were analyzed. Data from both the registry and the literature review confirmed that the main reasons for use of IL-1 blockers were the following: failure of previous treatment (n = 57, 61.3% and n = 964, 75.3%, respectively), persistence of disease activity with frequent attacks (n = 44, 47.3% and n = 1,023, 79.9%) and/or uncontrolled inflammatory syndrome (n = 46, 49.5% and n = 398, 31.1%), severe disease complication or associated comorbidities (n = 38, 40.9% and n = 390, 30.4%), and worsening of patients' quality of life (n = 36, 38.7% and n = 100, 7,8%). No reasons were specified for 12 (16.4%) JIRcohort patients and 154 (12%) patients in the literature.

Conclusion

In the absence of standardized indications for IL-1 inhibitors in crFMF, MKD, and TRAPS, these results could serve as a basis for developing a treat-to-target strategy that would help clinicians codify the therapeutic escalation with IL-1 inhibitors.

[Autoinflammation-A clinical and genetic challenge]

In the last two decades clinical rheumatological practice has been confronted with a steadily increasing number of autoinflammatory diseases, the immunological pathomechanisms of which have been elucidated and in part can be clinically well classified. Whereas targeted genetic diagnostics previously served to confirm a clinically suspected diagnosis, genetic sequencing technology has much improved and enables a new diagnostic approach via high-throughput sequencing, e.g., panel sequencing, whole exome and whole genome sequencing. Thus, the decision to make a diagnosis clinically and/or genetically, has become a daily challenge. This article contrasts the clinical, immunological and genetic aspects of autoinflammatory diseases.

Anakinra and canakinumab for patients with R92Q-associated autoinflammatory syndrome: a multicenter observational study from the AIDA Network

BACKGROUND

This study aims at describing the therapeutic outcome of patients carrying the R92Q variant in the TNFRSF1A gene treated with anakinra (ANA) or canakinumab (CAN) and identifying any factors predictive of complete response to IL-1 inhibition.

METHODS

Clinical data of patients treated with ANA or CAN for recurrent inflammatory attacks due to the presence of the R92Q variant were retrospectively collected and analysed.

RESULTS

Data about 20 treatment courses with IL-1 inhibitors (16 with ANA and 4 with CAN) from 19 patients were collected. Mean age at disease onset was 20.2 ± 14.8 years. In 5 cases (26%) the R92Q variant was found in a family member affected by recurrent fever. The therapeutic response was complete in 13(68%) and partial in 2 patients (11%); treatment failure was observed in 4 cases (21%). Median AIDAI decreased from 10 (interquartile range [IQR] = 28) to 0 (IQR = 1) at the 12-month follow-up visit (p < 0.001). Mean ESR and median CRP dropped respectively from 40.8 ± 24.8 to 9.1 ± 4.5 mm/h (p < 0.001) and from 3.0 (IQR = 1.9) to 0.3 (IQR = 0.3) mg/dl (p < 0.001) after 12 months of treatment. A steroid-sparing effect was observed from the third month of treatment (p < 0.01). Thirteen patients (65%) were still on treatment at the last follow-up visit (median duration of treatment 17 (IQR = 38) months). The presence of R92Q mutation in a symptomatic relative (p = 0.022), the relapsing remitting disease course (p < 0.001) and the presence of migratory erythematous skin rashes during fever attacks (p = 0.005) were associated with complete efficacy of IL-1 inhibitors.

CONCLUSIONS

R92Q patients showed a favourable response to ANA and CAN, particularly when the mutation segregated in a family member and when a relapsing-remitting disease course or TNF-α receptor-associated periodic syndrome (TRAPS) typical skin rash were observed. In the subgroup of patients not taking advantage of IL-1 blockage different molecular mechanisms underlying the autoinflammatory picture are likely to exist.

NLRP7: From inflammasome regulation to human disease

Nucleotide-binding oligomerization domain (NOD) and leucine-rich repeat (LRR)-containing receptors or NOD-like receptors (NLRs) are cytosolic pattern recognition receptors, which sense conserved microbial patterns and host-derived danger signals to elicit innate immune responses. The activation of several prototypic NLRs, including NLR and pyrin domain (PYD) containing (NLRP) 1, NLRP3 and NLR and caspase recruitment domain (CARD) containing (NLRC) 4, results in the assembly of inflammasomes, which are large, cytoplasmic multiprotein signalling platforms responsible for the maturation and release of the pro-inflammatory cytokines IL-1β and IL-18, and for the induction of a specialized form of inflammatory cell death called pyroptosis. However, the function of other members of the NLR family, including NLRP7, are less well understood. NLRP7 has been linked to innate immune signalling, but its precise role is still controversial as it has been shown to positively and negatively affect inflammasome responses. Inflammasomes are essential for homeostasis and host defence, but inappropriate inflammasome responses due to hereditary mutations and somatic mosaicism in inflammasome components and defective regulation have been linked to a broad spectrum of human diseases. A compelling connection between NLRP7 mutations and reproductive diseases, and in particular molar pregnancy, has been established. However, the molecular mechanisms by which NLRP7 mutations contribute to reproductive diseases are largely unknown. In this review, we focus on NLRP7 and discuss the current evidence of its role in inflammasome regulation and its implication in human reproductive diseases.

Is neutrophilic dermatosis a manifestation of familial Mediterranean fever?

Objectives: Familial Mediterranean fever (FMF) is the most frequent monogenic autoinflammatory disease. It is associated with MEFV mutations. Its main features are recurrent episodes of fever and serositis. Patients can display dermatological manifestations such as erysipelas-like erythema, generally considered as a neutrophilic dermatosis (ND). It has been suggested that FMF can be associated with other types of ND. Our aim was to perform a systematic review of the literature to assess the link between ND and FMF.Method: A systematic review of the literature was performed using MEDLINE from 1946 to 2018. Three independent investigators identified reports of non-erysipelas-like erythema neutrophilic dermatosis (NEND) associated with FMF, selected the criteria to establish the diagnosis of FMF and ND, and evaluated the link between the two conditions. FMF-associated NEND was supported by confirmation of both diagnoses and exclusion of other causes of ND.Results: Eighteen articles were selected. Nine articles reported FMF patients with the following NEND: neutrophilic panniculitis (n = 4), Sweet syndrome (n = 6), and pyoderma gangrenosum (n = 1). None of these cases was supported by histological confirmation, fulfilled diagnostic criteria for definitive or probable FMF, or confirmed the exclusion of all the most frequent diseases associated with NEND. As a result, there is insufficient evidence to support a potential relationship between NEND and FMF.Conclusions: The association between FMF and NEND remains unclear. In FMF patients with NEND, every differential diagnosis and alternative cause of NEND should be excluded before drawing any conclusions about a potential causal relationship.

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.

Mevalonate Kinase-Associated Diseases: Hunting for Phenotype-Genotype Correlation

Mevalonate kinase-associated diseases (MKAD) are caused by pathogenic mutations in the mevalonate kinase gene (MVK) and encompass several phenotypically different rare and hereditary autoinflammatory conditions. The most serious is a recessive systemic metabolic disease called mevalonic aciduria, and the most recently recognized is disseminated superficial actinic porokeratosis, a dominant disease limited to the skin. To evaluate a possible correlation between genotypes and (1) the different MKAD clinical subtypes or (2) the occurrence of severe manifestations, data were reviewed for all patients with MVK variants described in the literature (N = 346), as well as those referred to our center (N = 51). The genotypes including p.(Val377Ile) (homozygous or compound heterozygous) were more frequent in mild systemic forms but were also sometimes encountered with severe disease. We confirmed that amyloidosis was more prevalent in patients compound heterozygous for p.(Ile268Thr) and p.(Val377Ile) than in others and revealed new associations. Patients homozygous for p.(Leu264Phe), p.(Ala334Thr) or compound heterozygous for p.(His20Pro) and p.(Ala334Thr) had increased risk of severe neurological or ocular symptoms. All patients homozygous for p.(Leu264Phe) had a cataract. The variants associated with porokeratosis were relatively specific and more frequently caused a frameshift than in patients with other clinical forms (26% vs. 6%). We provide practical recommendations focusing on phenotype-genotype correlation in MKAD that could be helpful for prophylactic management.

Management of Monogenic IL-1 Mediated Autoinflammatory Diseases in Childhood

Monogenic Interleukin 1 (IL-1) mediated autoinflammatory diseases (AID) are rare, often severe illnesses of the innate immune system associated with constitutively increased secretion of pro-inflammatory cytokines. Clinical characteristics include recurrent fevers, inflammation of joints, skin, and serous membranes. CNS and eye inflammation can be seen. Characteristically, clinical symptoms are coupled with elevated inflammatory markers, such as C-reactive protein (CRP) and serum amyloid A (SAA). Typically, AID affect infants and children, but late-onset and atypical phenotypes are described. An in-depth understanding of autoinflammatory pathways and progress in molecular genetics has expanded the spectrum of AID. Increasing numbers of genetic variants with undetermined pathogenicity, somatic mosaicisms and phenotype variability make the diagnosis of AID challenging. AID should be diagnosed as early as possible to prevent organ damage. The diagnostic approach includes patient/family history, ethnicity, physical examination, specific functional testing and inflammatory markers (SAA, CRP) during, and in between flares. Genetic testing should be performed, when an AID is suspected. The selection of genetic tests is guided by clinical findings. Targeted and rapid treatment is crucial to reduce morbidity, mortality and psychosocial burden after an AID diagnosis. Management includes effective treat-to-target therapy and standardized, partnered monitoring of disease activity (e.g., AIDAI), organ damage (e.g., ADDI), patient/physician global assessment and health related quality of life. Optimal AID care in childhood mandates an interdisciplinary team approach. This review will summarize the current evidence of diagnosing and managing children with common monogenic IL-1 mediated AID.

Monogenic autoinflammatory disorders: Conceptual overview, phenotype, and clinical approach

Autoinflammatory diseases are conditions in which pathogenic inflammation arises primarily through antigen-independent hyperactivation of immune pathways. First recognized just over 2 decades ago, the autoinflammatory disease spectrum has expanded rapidly to include more than 40 distinct monogenic conditions. Related mechanisms contribute to common conditions such as gout and cardiovascular disease. Here, we review the basic concepts underlying the "autoinflammatory revolution" in the understanding of immune-mediated disease and introduce major categories of monogenic autoinflammatory disorders recognized to date, including inflammasomopathies and other IL-1-related conditions, interferonopathies, and disorders of nuclear factor kappa B and/or aberrant TNF activity. We highlight phenotypic presentation as a reflection of pathogenesis and outline a practical approach to the evaluation of patients with suspected autoinflammation.

Fast diagnostic test for familial Mediterranean fever based on a kinase inhibitor

BACKGROUND AND OBJECTIVE

Familial Mediterranean fever (FMF) is the most frequent hereditary autoinflammatory disease. Its diagnosis relies on a set of clinical criteria and a genetic confirmation on identification of biallelic pathogenic MEFV variants. MEFV encodes pyrin, an inflammasome sensor. Using a kinase inhibitor, UCN-01, we recently identified that dephosphorylation of FMF-associated pyrin mutants leads to inflammasome activation. The aim of this study was to assess whether quantifying UCN-01-mediated inflammasome activation could discriminate FMF patients from healthy donors (HD) and from patients with other inflammatory disorders (OID).

METHODS

Real-time pyroptosis and IL-1β secretion were monitored in response to UCN-01 in monocytes from FMF patients (n=67), HD (n=71) and OID patients (n=40). Sensitivity and specificity of the resulting diagnostic tests were determined by receiver operating characteristic curve analyses.

RESULTS

Inflammasome monitoring in response to UCN-01 discriminates FMF patients from other individuals. Pyroptosis assessment leads to a fast FMF diagnosis while combining pyroptosis and IL-1β dosage renders UCN-01-based assays highly sensitive and specific. UCN-01-triggered monocytes responses were influenced by MEFV gene dosage and MEFV mutations in a similar way as clinical phenotypes are.

CONCLUSIONS

UCN-01-based inflammasome assays could be used to rapidly diagnose FMF, with high sensitivity and specificity.

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.

Phenotypic Associations of PSTPIP1 Sequence Variants in PSTPIP1-Associated Autoinflammatory Diseases

Pathogenic variants in the PSTPIP1 gene cause pyogenic sterile arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome. They were also identified in a broad spectrum of phenotypes. As their interpretation is sometimes challenging, we discuss the genotype-phenotype association in PSTPIP1-associated autoinflammatory diseases (PAIDs) in light of a recent consensus classification of variant pathogenicity. Only 7 of 39 (18%) of the PSTPIP1 variants found in all reported cases and our national reference center (161 patients [114 probands]) were pathogenic. They were clearly associated with PAPA and PSTPIP1-associated myeloid-related proteinemia inflammatory syndrome (PAMI), reflecting a variable clinical expression of PAIDs.

Computational Modeling of NLRP3 Identifies Enhanced ATP Binding and Multimerization in Cryopyrin-Associated Periodic Syndromes

Cyropyrin-associated periodic syndromes (CAPS) are clinically distinct syndromes that encompass a phenotypic spectrum yet are caused by alterations in the same gene, NLRP3. Many CAPS cases and other NLRP3-autoinflammatory diseases (NLRP3-AIDs) are directly attributed to protein-coding alterations in NLRP3 and the subsequent dysregulation of the NLRP3 inflammasome leading to IL-1β-mediated inflammatory states. Here, we used bioinformatics tools, computational modeling, and computational assessments to explore the proteomic consequences of NLRP3 mutations, which potentially drive NLRP3 inflammasome dysregulation. We analyzed 177 mutations derived from familial cold autoinflammatory syndrome (FCAS), Muckle-Wells Syndrome (MWS), and the non-hereditary chronic infantile neurologic cutaneous and articular syndrome, also known as neonatal-onset multisystem inflammatory disease (CINCA/NOMID), as well as other NLRP3-AIDs. We found an inverse relationship between clinical severity and the severity of predicted structure changes resulting from mutations in NLRP3. Bioinformatics tools and computational modeling revealed that NLRP3 mutations that are predicted to be structurally severely-disruptive localize around the ATP binding pocket and that specific proteo-structural changes to the ATP binding pocket lead to enhanced ATP binding affinity by altering hydrogen-bond and charge interactions. Furthermore, we demonstrated that NLRP3 mutations that are predicted to be structurally mildly- or moderately-disruptive affect protein-protein interactions, such as NLRP3-ASC binding and NLRP3-NLRP3 multimerization, enhancing inflammasome formation and complex stability. Taken together, we provide evidence that proteo-structural mechanisms can explain multiple mechanisms of inflammasome activation in NLRP3-AID.

INSAID Variant Classification and Eurofever Criteria Guide Optimal Treatment Strategy in Patients with TRAPS: Data from the Eurofever Registry

BACKGROUND

TNF receptor-associated periodic syndrome (TRAPS) is a rare autoinflammatory disease caused by dominant mutation of the TNF super family receptor 1A (TNFRSF1A) gene. Data regarding long-term treatment outcomes are lacking.

OBJECTIVE

To assess correlations of genotype-phenotypes in patients with TRAPS, as defined by the International Study Group for Systemic Autoinflammatory Diseases (INSAID) classification and Eurofever criteria, with treatment responses.

METHODS

Data from 226 patients with variants of the TNFRSF1A gene and enrolled in the Eurofever registry were classified according to the INSAID classification in groups A (pathogenic or likely pathogenic variants), B (variants of uncertain significance or not classified variants), and C (benign or likely benign variants) and screened for Eurofever criteria.

RESULTS

In group A (127 of 226 patients, 56%), all fulfilled Eurofever criteria and 20 of 127 patients (16%) developed AA amyloidosis. In group B (78 of 226 patients, 35%), 40 of 78 patients (51%) did not fulfill Eurofever criteria, displaying a lower incidence of abdominal pain (P < .02) and higher efficacy rate of on-demand nonsteroidal anti-inflammatory drugs (P < .02) and colchicine (P < .001). Group C (21 of 226 patients, 9%) presented a milder disease (P < .02) and none fulfilled Eurofever criteria. Anti-IL-1 drugs were the most frequently used in patients fulfilling Eurofever criteria, with the highest efficacy rate (>85% complete response). No patients on anti-IL-1 treatments developed AA amyloidosis, and 7 women with a history of failure to conceive had successful pregnancies.

CONCLUSION

Anti-IL-1 drugs are the best maintenance treatment in patients with TRAPS. The diagnosis of TRAPS should be considered very carefully in patients of group B not fulfilling Eurofever criteria and group C, and colchicine may be preferable as the first maintenance treatment.

Familial Mediterranean fever, from pathogenesis to treatment: a contemporary review

Familial Mediterranean fever (FMF) (OMIM #249100) is the most common hereditary autoinflammatory disease in the world. FMF is caused by gain of function mutations of MEFV gene which encodes an immune regulatory protein, pyrin. Over the last few years, we have witnessed several new developments in the pathogenesis, genetic testing, diagnosis, comorbidities, disease related damage and treatment approaches to FMF. Elucidation of some of the pathogenic mechanisms has led to the discovery of pathways involved in inflammatory, metabolic, cardiovascular and degenerative diseases. The use of next generation sequencing in FMF has revealed many new gene variants whose clinical significance may be clarified by developing functional assays and biomarkers. Clinically, although FMF is considered an episodic disease characterized by brief attacks, recent systematic studies have defined several associated chronic inflammatory conditions. Colchicine is the mainstay of FMF treatment, and interleukin (IL)-1 antagonists are the treatment of choice in refractory or intolerant cases. Experience of IL-1 antagonists, anakinra and canakinumab, is now available in thousands of colchicine resistant or intolerant FMF patients. In this contemporary review, we surveyed current FMF knowledge in the light of these recent advances.

ISSAID/EMQN Best Practice Guidelines for the Genetic Diagnosis of Monogenic Autoinflammatory Diseases in the Next-Generation Sequencing Era

BACKGROUND

Monogenic autoinflammatory diseases are caused by pathogenic variants in genes that regulate innate immune responses, and are characterized by sterile systemic inflammatory episodes. Since symptoms can overlap within this rapidly expanding disease category, accurate genetic diagnosis is of the utmost importance to initiate early inflammation-targeted treatment and prevent clinically significant or life-threatening complications. Initial recommendations for the genetic diagnosis of autoinflammatory diseases were limited to a gene-by-gene diagnosis strategy based on the Sanger method, and restricted to the 4 prototypic recurrent fevers (MEFV, MVK, TNFRSF1A, and NLRP3 genes). The development of best practices guidelines integrating critical recent discoveries has become essential.

METHODS

The preparatory steps included 2 online surveys and pathogenicity annotation of newly recommended genes. The current guidelines were drafted by European Molecular Genetics Quality Network members, then discussed by a panel of experts of the International Society for Systemic Autoinflammatory Diseases during a consensus meeting.

RESULTS

In these guidelines, we combine the diagnostic strength of next-generation sequencing and recommendations to 4 more recently identified genes (ADA2, NOD2, PSTPIP1, and TNFAIP3), nonclassical pathogenic genetic alterations, and atypical phenotypes. We present a referral-based decision tree for test scope and method (Sanger versus next-generation sequencing) and recommend on complementary explorations for mosaicism, copy-number variants, and gene dose. A genotype table based on the 5-category variant pathogenicity classification provides the clinical significance of prototypic genotypes per gene and disease.

CONCLUSIONS

These guidelines will orient and assist geneticists and health practitioners in providing up-to-date and appropriate diagnosis to their patients.

Validation of the new classification criteria for hereditary recurrent fever in an independent cohort: experience from the JIR Cohort Database

OBJECTIVE

The new classification criteria for the hereditary recurrent fever (HRF) syndrome [cryopyrin-associated periodic syndrome (CAPS), TNF-α receptor-associated periodic syndrome (TRAPS), FMF and mevalonate kinase deficiency] have been published recently. These criteria define two core sets of criteria for each HRF: mixed criteria, including genetic and clinical variables, and clinical criteria, relying on clinical variables only. Our aim was to validate the criteria for HRF in an independent cohort, the JIR Cohort database, an international repository of systemic inflammatory diseases.

METHODS

We enrolled patients with HRF, periodic fever, adenitis, pharyngitis and aphthous stomatitis syndrome (PFAPA) and syndrome of undefined recurrent fever (SURF). A score ranging from zero to two was attributed to their respective genotypes: zero (no mutation), one (non-confirmatory genotype) or two (confirmatory genotype). The criteria were applied to all patients based on genotype scoring. The treating physician's diagnosis served as the gold standard for the determination of specificity.

RESULTS

We included 455 patients. The classification criteria showed excellent specificity for CAPS and TRAPS (98% specificity each), fair specificity for FMF (88%), but poor specificity for mevalonate kinase deficiency (58%). Sub-analysis showed excellent accuracy of the mixed criteria for all four HRFs. Misclassification was mainly attributable to clinical criteria sets, with false-positive patients in all four HRF clinical criteria sets.

CONCLUSION

This study represents the final validation step of the HRF classification criteria as recommended by the ACR. Genetic data appear to be necessary to classify patients with HRF correctly.

Is gene panel sequencing more efficient than clinical-based gene sequencing to diagnose autoinflammatory diseases? A randomized study

The aim of this study was to compare the effectiveness of the gene-panel next-generation sequencing (NGS) strategy versus the clinical-based gene Sanger sequencing for the genetic diagnosis of autoinflammatory diseases (AIDs). Secondary goals were to describe the gene and mutation distribution in AID patients and to evaluate the impact of the genetic report on the patient's medical care and treatment. Patients with AID symptoms were enrolled prospectively and randomized to two arms, NGS (n = 99) (32-55 genes) and Sanger sequencing (n = 197) (one to four genes). Genotypes were classified as 'consistent/confirmatory', 'uncertain significance' or 'non-contributory'. The proportion of patients with pathogenic genotypes concordant with the AID phenotype (consistent/confirmatory) was significantly higher with NGS than Sanger sequencing [10 of 99 (10·1%) versus eight of 197 (4·1%)]. MEFV, ADA2 and MVK were the most represented genes with a consistent/confirmed genotype, whereas MEFV, NLRP3, NOD2 and TNFRSF1A were found in the 'uncertain significance' genotypes. Six months after the genetic report was sent, 54 of 128 (42·2%) patients had received effective treatment for their symptoms; 13 of 128 (10·2%) had started treatment after the genetic study. For 59 of 128 (46%) patients, the results had an impact on their overall care, independent of sequencing group and diagnostic conclusion. Targeted NGS improved the diagnosis and global care of patients with AIDs.

Gut Microbiota between Environment and Genetic Background in Familial Mediterranean Fever (FMF)

The gastrointestinal tract hosts the natural reservoir of microbiota since birth. The microbiota includes various bacteria that establish a progressively mutual relationship with the host. Of note, the composition of gut microbiota is rather individual-specific and, normally, depends on both the host genotype and environmental factors. The study of the bacterial profile in the gut demonstrates that dominant and minor phyla are present in the gastrointestinal tract with bacterial density gradually increasing in oro-aboral direction. The cross-talk between bacteria and host within the gut strongly contributes to the host metabolism, to structural and protective functions. Dysbiosis can develop following aging, diseases, inflammatory status, and antibiotic therapy. Growing evidences show a possible link between the microbiota and Familial Mediterranean Fever (FMF), through a shift of the relative abundance in microbial species. To which extent such perturbations of the microbiota are relevant in driving the phenotypic manifestations of FMF with respect to genetic background, remains to be further investigated.

[Genetic diagnostics of autoinflammatory diseases]

Autoinflammatory syndromes are characterized by periodic febrile attacks in combination with increased inflammatory markers. The dysregulation of different cellular signaling pathways leads to an excessive immune response, which can in turn promote multisystemic inflammatory processes. Due to overlapping symptoms, variable expressivity and pleiotropy, a purely clinical diagnosis of autoinflammatory diseases is difficult in many cases. Because an early and definitive diagnosis can greatly improve the quality of life of many patients, molecular genetic methods have become an important part of the diagnostic process. With the development of next-generation sequencing (NGS), the genetic diagnosis of patients with autoinflammatory diseases has significantly improved. Considerable progress has not only been made in the genetic characterization of undiagnosed patients, but additionally in identifying numerous new disease-associated genes; however, the plethora of molecular genetic analytical methods makes it difficult to select the method with the highest diagnostic specificity and sensitivity. The NGS technologies have also led to a large increase in the number of identified variants, making the clinical evaluation of these variants more complex. Consensus-driven and standardized molecular diagnostic guidelines, both for the diagnostic process and for the interpretation of the obtained results, have therefore become essential.

Differential mutational profiles of familial Mediterranean fever in North Africa

Familial Mediterranean fever (FMF) is a recessive autoinflammatory disease, mainly occurring in the eastern Mediterranean. In these populations, the five FMF founder mutations are differently distributed. In Algeria, the FMF-causing variants remain poorly explored. This retrospective study aims to report the mutational profile of Algerian FMF patients and to compare it with North African FMF patients. One hundred eighty-three unrelated patients clinically suspected of FMF were recruited from various Algerian hospitals (2007-2015) and tested for mutations in exon 10 of MEFV gene. Molecular analysis identified 144 mutant alleles among 87 of 183 patients (47.5%). p.M694I was the most prevalent pathogenic allele, accounting for 63.2% of mutant alleles, followed by p.M694V and p.M680I occurring with a same frequency (14.5%). Others, p.A744S (6.2%) and p.I692del (1.3%), are less frequent. Interestingly, p.M694I was the most recurrent in patients with renal AA-amyloidosis. Our results provide the first genetic data on FMF in Algeria, demonstrating the predominance of p.M694I and the absence of p.V726A, compared to other North African countries (Morocco, Tunisia, and Egypt). In conclusion, North African FMF patients display differential mutational profiles that may result from the difference in ethnic origin and the genetic heterogeneity among these populations.

Spectrum of MEFV Variants and Genotypes among Clinically Diagnosed FMF Patients from Southern Lebanon

Background: Familial Mediterranean Fever (FMF) is an autosomal recessive auto-inflammatory disease characterized by pathogenic variants in the MEFV gene, with allele frequencies greatly varying between countries, populations and ethnic groups. Materials and methods: In order to analyze the spectrum of MEFV variants and genotypes among clinically diagnosed FMF patients from South Lebanon, data were collected from 332 participants and 23 MEFV variants were screened using a Real-Time PCR Kit. Results: The mean age at symptom onset was 17.31 ± 13.82 years. The most prevalent symptoms were abdominal pain, fever and myalgia. MEFV molecular analysis showed that 111 patients (63.79%) were heterozygous, 16 (9.20%) were homozygous, and 47 (27.01%) carried two variants or more. E148Q was the most encountered variant among heterozygous subjects. E148Q/M694V was the most frequent in the compound heterozygous/complex genotype group, while M694I was the most common among homozygous patients. Regarding allele frequencies, M694V was the most common variant (20.7%), followed by E148Q (17.1%), V726A (15.7%) and M694I (13.2%). Conclusion: The high percentage of heterozygous patients clinically diagnosed as FMF highlights the pseudo-dominant transmission of the disease in Lebanon and emphasizes the importance of molecular testing for a more accurate diagnosis and better management and treatment of FMF.

Clinical Features at Onset and Genetic Characterization of Pediatric and Adult Patients with TNF-α Receptor-Associated Periodic Syndrome (TRAPS): A Series of 80 Cases from the AIDA Network

This study explores demographic, clinical, and therapeutic features of tumor necrosis factor receptor-associated periodic syndrome (TRAPS) in a cohort of 80 patients recruited from 19 Italian referral Centers. Patients' data were collected retrospectively and then analyzed according to age groups (disease onset before or after 16 years) and genotype (high penetrance (HP) and low penetrance (LP) TNFRSF1A gene variants). Pediatric- and adult-onset were reported, respectively, in 44 and 36 patients; HP and LP variants were found, respectively, in 32 and 44 cases. A positive family history for recurrent fever was reported more frequently in the pediatric group than in the adult group (p < 0.05). With reference to clinical features during attacks, pericarditis and myalgia were reported more frequently in the context of adult-onset disease than in the pediatric age (with p < 0.01 and p < 0.05, respectively), while abdominal pain was present in 84% of children and in 25% of adults (p < 0.01). Abdominal pain was significantly associated also to the presence of HP mutations (p < 0.01), while oral aphthosis was more frequently found in the LP variant group (p < 0.05). Systemic amyloidosis occurred in 25% of subjects carrying HP variants. As concerns laboratory features, HP mutations were significantly associated to higher ESR values (p < 0.01) and to the persistence of steadily elevated inflammatory markers during asymptomatic periods (p < 0.05). The presence of mutations involving a cysteine residue, abdominal pain, and lymphadenopathy during flares significantly correlated with the risk of developing amyloidosis and renal impairment. Conversely, the administration of colchicine negatively correlated to the development of pathologic proteinuria (p < 0.05). Both NSAIDs and colchicine were used as monotherapy more frequently in the LP group compared to the HP group (p < 0.01). Biologic agents were prescribed to 49 (61%) patients; R92Q subjects were more frequently on NSAIDs monotherapy than other patients (p < 0.01); nevertheless, they required biologic therapy in 53.1% of cases. At disease onset, the latest classification criteria for TRAPS were fulfilled by 64/80 (80%) patients (clinical plus genetic items) and 46/80 (57.5%) patients (clinical items only). No statistically significant differences were found in the sensitivity of the classification criteria according to age at onset and according to genotype (p < 0.05). This study describes one of the widest cohorts of TRAPS patients in the literature, suggesting that the clinical expression of this syndrome is more influenced by the penetrance of the mutation rather than by the age at onset itself. Given the high phenotypic heterogeneity of the disease, a definite diagnosis should rely on both accurate working clinical assessment and complementary genotype.

RIP-roaring inflammation: RIPK1 and RIPK3 driven NLRP3 inflammasome activation and autoinflammatory disease

Autoinflammatory syndromes comprise a spectrum of clinical disorders characterised by recurrent, inflammatory episodes, many of which result from the release of the pro-inflammatory cytokine, interleukin-1β (IL-1β). Inflammation and programmed cell death are tightly linked, and lytic forms of cell death, such as necroptosis and pyroptosis, are considered to be inflammatory due to the release of damage-associated molecular patterns (DAMPs). In contrast, apoptosis is traditionally regarded as immunologically silent. Recent studies, however, have uncovered a high degree of crosstalk between cell death and inflammatory signalling pathways, and effectively consolidated them into one interconnected network that converges on NLRP3 inflammasome-mediated activation of IL-1β. The receptor-interacting protein kinases (RIPK) 1 and 3 are central to this network, as highlighted by the fact that mutations in genes encoding repressors of RIPK1 and/or RIPK3 activity can lead to heightened inflammation, particularly via NLRP3 inflammasome activation. In this review, we give an overview of extrinsic cell death and inflammatory signalling pathways, and then highlight the growing number of autoinflammatory diseases that are associated with aberrant cell death and inflammasome activation.

Selective inhibition of NLRP3 inflammasome by designed peptide originating from ASC

NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome is a multiprotein complex which forms within cells in response to various microbial and self-derived triggers. Mutations in the gene encoding NLRP3 cause rare cryopyrin-associated periodic syndromes (CAPS) and growing evidence links NLRP3 inflammasome to common diseases such as Alzheimer´s disease. In order to modulate different stages of NLRP3 inflammasome assembly nine peptides whose sequences correspond to segments of inflammasome components NLRP3 and apoptosis-associated speck-like protein containing a CARD (ASC) were selected. Five peptides inhibited IL-1β release, caspase-1 activation and ASC oligomerization in response to soluble and particulate NLRP3 triggers. Modulatory peptides also attenuated IL-1β maturation induced by constitutive CAPS-associated NLRP3 mutants. Peptide corresponding to H2-H3 segment of ASC pyrin domain selectively inhibited NLRP3 inflammasome by binding to NLRP3 pyrin domain in the micromolar range. The peptide had no effect on AIM2 and NLRC4 inflammasomes as well as NF-κB pathway. The peptide effectively dampened neutrophil infiltration in the silica-induced peritonitis and when equipped with Antennapedia or Angiopep-2 motifs crossed the blood-brain barrier in a mouse model. Our study demonstrates that peptides represent an important tool for targeting multiprotein inflammatory complexes and can serve as the basis for the development of novel anti-inflammatory strategies for neurodegeneration.

A case of cryopyrin-associated periodic fever syndrome during canakinumab administration complicated by inflammatory bowel disease

Cryopyrin-associated periodic fever syndrome (CAPS) is a highly debilitating disorder, which is characterized by unregulated interleukin-1β production driven by autosomal dominantly inherited mutations in the NLRP3 gene. Patients with CAPS often present with early-onset episodes of fever and rash. These patients also present with variable systemic signs and symptoms, such as arthritis, sensorineural hearing loss, chronic aseptic meningitis, and skeletal abnormalities, but minimal gastrointestinal symptoms. Recently, effective therapies for CAPS targeted against interleukin-1 have become available. We report a case of a young Japanese woman with CAPS who developed inflammatory bowel disease during canakinumab therapy. The patient had colostomy after intestinal perforation and changed canakinumab to infliximab. To the best of our knowledge, this is the first report of a case of inflammatory bowel disease secondary to CAPS complicated by gastrointestinal symptoms and arthritis which canakinumab could not control. Patients with CAPS who have symptoms that cannot be controlled by canakinumab should be considered for possible co-morbidities.

Blood-based test for diagnosis and functional subtyping of familial Mediterranean fever

BACKGROUND AND OBJECTIVE

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease (AID) worldwide. The disease is caused by mutations in the MEFV gene encoding the inflammasome sensor Pyrin. Clinical diagnosis of FMF is complicated by overlap in symptoms with other diseases, and interpretation of genetic testing is confounded by the lack of a clear genotype-phenotype association for most of the 340 reported MEFV variants. In this study, the authors designed a functional assay and evaluated its potential in supporting FMF diagnosis.

METHODS

Peripheral blood mononuclear cells (PBMCs) were obtained from patients with Pyrin-associated autoinflammation with an FMF phenotype (n=43) or with autoinflammatory features not compatible with FMF (n=8), 10 asymptomatic carriers and 48 healthy donors. Sera were obtained from patients with distinct AIDs (n=10), and whole blood from a subset of patients and controls. The clinical, demographic, molecular genetic factors and other characteristics of the patient population were assessed for their impact on the diagnostic test read-out. Interleukin (IL)-1β and IL-18 levels were measured by Luminex assay.

RESULTS

The ex vivo colchicine assay may be performed on whole blood or PBMC. The functional assay robustly segregated patients with FMF from healthy controls and patients with related clinical disorders. The diagnostic test distinguished patients with classical FMF mutations (M694V, M694I, M680I, R761H) from patients with other MEFV mutations and variants (K695R, P369S, R202Q, E148Q) that are considered benign or of uncertain clinical significance.

CONCLUSION

The ex vivo colchicine assay may support diagnosis of FMF and functional subtyping of Pyrin-associated autoinflammation.

Characteristics of patients with familial Mediterranean fever in Denmark: a retrospective nationwide register-based cohort study

Objectives: To investigate epidemiology, demography, and genetic and clinical characteristics of patients with familial Mediterranean fever (FMF) in Denmark. Method: In this population-based, cross-sectional cohort study, we identified FMF patients from discharge diagnoses using ICD-10 codes in the Danish National Patient Register, and linked data from the Danish Civil Registration System and laboratory databases for results of MEFV gene variant screening. Results: We identified 495 FMF patients (prevalence 1:11 680) with a median age of 29 years and a female ratio of 51%. The median age at diagnosis of FMF was 13 (IQR 7-22) years, with an estimated median diagnostic delay of 3 (IQR 0.7-6.9) years. The predominant ethnicities were Turkish (41.8%), Lebanese (15.8%), Syrian (6.5%), South-West Asian (7.9%), and South-East Asian (3.0%). The MEFV genotype distribution was 18.7% homozygous, 21.2% compound heterozygous, 32.0% heterozygous, 11.0% with complex alleles or unresolved zygosity, and 17.1% with no detected variants. M694V was the most prevalent variant in the overall cohort (32.5%). Homozygous or compound heterozygous MEFV exon 10 variants were associated with younger age at diagnosis (p < 0.001) and reduced number of hospital contacts before diagnosis (p = 0.008). The Charlson Comorbidity Index was ≥ 2 in 8.1% of patients. The prevalence of amyloidosis was 1.0%. Conclusions: FMF in Denmark is rare and patients are mainly of Eastern Mediterranean ethnicity. Diagnostic delay was long but patients with exon 10 MEFV variants were diagnosed at a younger age. Prolonged diagnostic delay is probably caused by lack of FMF awareness in the Danish healthcare system.

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.

The association of MEFV gene mutations with the disease risk and severity of systemic juvenile idiopathic arthritis

BACKGROUND

Systemic juvenile idiopathic arthritis (sJIA) has many clinical features overlapping with familial Mediterranean fever (FMF), which is caused by mutations in MEFV gene. And FMF patients were easily misdiagnosed as sJIA in China. So we speculate that MEFV is critical genetic background for sJIA and influences patients' severity. In this study, we aim to figure out whether MEFV mutations are risk factor for the occurrence of sJIA and to study the association of MEFV mutations with disease severity of sJIA patients.

METHODS

The present study includes 57 sJIA children and 2573 healthy controls. Odd ratio with 95% confidence interval based on allelic frequency of MEFV mutations or variants was used to evaluate their contribution to sJIA susceptibility. Meta-analysis was then performed to reach comprehensive conclusion. All included sJIA patients were grouped by presence and number of MEFV mutations. Clinical data and indicators of disease severity were compared among different groups. Multiple linear regression method was used to find out whether the number of MEFV variants is associated with the severity of sJIA. Kaplan-Meier curves and log rank test were used to estimate the probability of the first relapse.

RESULTS

The MEFV mutations of our subjects predominantly existed in exons 2 and 3. No significant difference was found in allelic frequency between sJIA children and healthy controls. Meta-analysis demonstrated that p.M694V/I was a risk factor for sJIA (pooled OR: 7.13, 95% CI: 3.01-16.89). The relative period of activity was significantly lower in the one mutation group than those with more than one mutation (p = 0.0194). However, no relevance was found in multiple linear regression models.

CONCLUSIONS

The mutation p.M694V/I in MEFV might be a risk factor for sJIA. SJIA patients carrying more than one heterozygous mutation in MEFV tend to be more severe than those containing only one, but studies in other cohort of patients need to be performed to validate it.

Revisiting TNF Receptor-Associated Periodic Syndrome (TRAPS): Current Perspectives

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is an autosomal dominant autoinflammatory syndrome characterized by prolonged and recurrent episodes of fever, abdominal and/or chest pain, arthralgia, myalgia, and erythematous rash. TRAPS is associated with heterozygous variants in the TNFRSF1A gene, which encodes the TNFR1 (tumor necrosis factor receptor 1) receptor. Disease-causing variants are found exclusively in the extracellular domain of TNFR1 and affect receptor structure and binding to the TNF ligand. The precise mechanism of the disease is still unclear, but it is thought that intracellular accumulation of misfolded mutant protein leads to endoplasmic reticulum stress and enhanced inflammatory responses through constitutive activation of various immune pathways. Other possible mechanisms contributing to the disease pathogenesis include defective receptor shedding, TNF-induced cell death, production of reactive oxygen species, and autophagy impairment. Patients' leucocytes are hyperresponsive to stimulation and produce elevated levels of proinflammatory cytokines. Systemic autoimmune (AA) amyloidosis is an important cause of morbidity and mortality in TRAPS. Over the last two decades, new therapies have changed the progression and outcome of the disease. In this review, we summarize clinical data from 209 patients with validated pathogenic variants reported in the literature and discuss TRAPS diagnosis, pathogenesis, and treatment options.

Systemic autoinflammatory diseases

Systemic autoinflammatory diseases (SAIDs) are a growing group of disorders caused by a dysregulation of the innate immune system leading to episodes of systemic inflammation. In 1997, MEFV was the first gene identified as disease causing for Familial Mediterranean Fever, the most common hereditary SAID. In most cases, autoinflammatory diseases have a strong genetic background with mutations in single genes. Since 1997 more than 30 new genes associated with autoinflammatory diseases have been identified, affecting different parts of the innate immune system. Nevertheless, for at least 40-60% of patients with phenotypes typical for SAIDs, a distinct diagnosis cannot be met, leading to undefined SAIDs (uSAIDs). However, SAIDs can also be of polygenic or multifactorial origin, with environmental influence modulating the phenotype. The implementation of a disease continuum model combining the adaptive and the innate immune system with autoinflammatory and autoimmune diseases shows the complexity of SAIDs and the importance of new methods to elucidate molecular changes and causative factors in SAIDs. Diagnosis is often based on clinical presentation and genetic testing. The timeline from onset to diagnosis takes up to 7.3 years, highlighting the indisputable need to identify new treatment and diagnostic targets. Recently, other factors are under investigation as additional contributors to the pathogenesis of SAIDs. This review gives an overview of pathogenesis and etiology of SAIDs, and summarizes recent diagnosis and treatment options.

The French paediatric cohort of Castleman disease: a retrospective report of 23 patients

BACKGROUND

Castleman disease (CD) is a rare non-malignant lymphoproliferation of undetermined origin. Two major disease phenotypes can be distinguished: unicentric CD (UCD) and multicentric CD (MCD). Diagnosis confirmation is based on histopathological findings in a lymph node. We attempted to survey all cases of paediatric CD identified to date in France to set up a national registry aiming to improve CD early recognition, treatment and follow-up, within the context of a new national reference center (http://www.castleman.fr).

METHODS

In 2016, we e-mailed a questionnaire to members of the French paediatric immunohaematology society, the paediatric rheumatology society and the Reference Centre for Castleman Disease to retrospectively collect cases of paediatric CD (first symptoms before age 18 years). Anatomopathological confirmation was mandatory.

RESULTS

We identified 23 patients (12 girls) with a diagnosis of UCD (n = 17) and MCD (n = 6) between 1994 and 2018. The mean age at first symptoms was 11.47 ± 4.23 years for UCD and 8.3 ± 3.4 years for MCD. The mean diagnosis delay was 8.16 ± 10.32 months for UCD and 5.16 ± 5.81 years for MCD. In UCD, the initial symptoms were isolated lymph nodes (n = 10) or lymph node associated with other symptoms (n = 7); fever was present in 3 patients. Five patients with MCD presented fever. No patients had HIV or human herpesvirus 8 infection. Autoinflammatory gene mutations were investigated in five patients. One patient with MCD carried a K695R heterozygous mutation in MEFV, another patient with MCD and Duchenne myopathy carried two variants in TNFRSF1A and one patient with UCD and fever episodes carried two heterozygous mutations, in IL10RA and IL36RN, respectively. Treatment of UCD was mainly surgical resection, steroids, and radiotherapy. Treatment of MCD included tocilizumab, rituximab, anakinra, steroids, chemotherapy, and splenectomy. Overall survival after a mean of 6.1 ± 6.4 years of follow-up, was 100% for both forms.

CONCLUSION

Paediatric CD still seems underdiagnosed, with a significant diagnosis delay, especially for MCD, but new international criteria will help in the future. Unlike adult CD, which is strongly associated with HIV and human herpesvirus 8 infection, paediatric CD could be favored by primary activation of innate immunity and may affect life expectancy less.

Current and future advances in genetic testing in systemic autoinflammatory diseases

Systemic autoinflammatory diseases (SAIDs) are a group of inflammatory disorders caused by dysregulation in the innate immune system that leads to enhanced immune responses. The clinical diagnosis of SAIDs can be difficult since individually these are rare diseases with considerable phenotypic overlap. Most SAIDs have a strong genetic background, but environmental and epigenetic influences can modulate the clinical phenotype. Molecular diagnosis has become essential for confirmation of clinical diagnosis. To date there are over 30 genes and a variety of modes of inheritance that have been associated with monogenic SAIDs. Mutations in the same gene can lead to very distinct phenotypes and can have different inheritance patterns. In addition, somatic mutations have been reported in several of these conditions. New genetic testing methods and databases are being developed to facilitate the molecular diagnosis of SAIDs, which is of major importance for treatment, prognosis and genetic counselling. The aim of this review is to summarize the latest advances in genetic testing for SAIDs and discuss potential obstacles that might arise during the molecular diagnosis of SAIDs.

Improvement of MEFV gene variants classification to aid treatment decision making in familial Mediterranean fever

OBJECTIVE

FMF is an inherited autoinflammatory syndrome caused by mutations in the MEFV gene. MEFV variants are still largely classified as acvariant of uncertain significance, or with unresolved classification, posing significant challenges in FMF diagnosis. Rare Exome Variant Ensemble Learner (REVEL) is a recently developed variant metapredictor tool. To reduce the number of MEFV variants with ambiguous classification, we extracted REVEL scores for all missense variants present in the INFEVERS database, and analysed its correlation with expert-based classification and localization in the MEFV-encoded pyrin functional domains.

METHODS

The data set of 216 MEFV missense variants was divided into four categories (likely benign, variant of uncertain significance, likely pathogenic and unresolved). Variants were plotted onto the pyrin protein, the distribution of REVEL scores in each category was computed and means, confidence intervals, and area under the receiver operating curve were calculated.

RESULTS

We observed a non-random distribution of pathogenic variants along the pyrin functional domains. The REVEL scores demonstrated a good correlation with the consensus classification of the International Study Group for Systemic Autoinflammatory Diseases. Sensitivity, specificity and accuracy were calculated for different cut-off values of REVEL scores and a gene-specific-threshold of 0.298 was computed with confidence boundary limits. This cut-off value allowed us to propose a reclassification of 96 MEFV gene variants, thus reducing the variant of uncertain significance proportion from 61.6% to 17.6%.

CONCLUSION

The combination of available expert information with sensitive predictor tools could result in a more accurate interpretation of clinical consequences of MEFV gene variants, and to a better genetic counselling and patient management.

The grandfather's fever

An 86-year-old Caucasian man had prior episodes of fever (up to 38 °C), mild abdominal pain, tachycardia, and malaise in the last 3 months, lasting 2-3 days. He never suffered from abdominal or chest pain, rash, or arthralgia. Major causes of fever were excluded (pulmonary, urinary, abdomen, skin infections, neoplasms, and major rheumatologic disorders). The patient was native of Altamura with a family history of familial Mediterranean fever (FMF). The genetic testing confirmed the presence of MEFV gene variants c.442G>C (E148Q) on exon 2 and c.2282G>A (R761H) on exon 10, all in heterozygosity. Mildly elevated serum transaminases suggested an ongoing form of FMF hepatitis on nonalcoholic liver steatosis. The patient started colchicine 1 mg/day that induced symptom control and normalization of inflammatory markers, hyperbilirubinemia, and markers of cholestasis. Symptoms of FMF can appear at any age in life and our patient represents a very late-onset clinical case. The Apulian region has a consistent clustering of MEFV variants and FMF families with affected individuals in multiple consecutive generations. Families show unique clinical features and rare signs of secondary amyloidosis without kidney damage. Genetic and environmental bases of this phenotypic variant are under scrutiny. Colchicine lifetime remains the mainstay of treatment in FMF patients. KEY POINTS: • Familial Mediterranean fever (FMF) is the most frequent hereditary monogenic recurrent fever syndrome, and symptoms can appear at any age in life. • Late-onset FMF approaches 30% in late adulthood, but in general, onset of FMF after the age of 40 (late onset FMF) is rare, usually associated with M694V heterozygosity. • In a local cluster of FMF families (Altamura, Puglia, Southern Italy), we report a very late-onset FMF (variants E148Q, R761H) in an 86-year-old patient with a positive family history of FMF in two generations of descendants. • While lifetime colchicine remains the mainstay of treatment in FMF patients, prospective studies need to identify the characteristics of several phenotypic variants accounting for (very)-late onset FMF.

In-silico Analysis of NF1 Missense Variants in ClinVar: Translating Variant Predictions into Variant Interpretation and Classification

Background: With the advent of next-generation sequencing in genetic testing, predicting the pathogenicity of missense variants represents a major challenge potentially leading to misdiagnoses in the clinical setting. In neurofibromatosis type 1 (NF1), where clinical criteria for diagnosis may not be fully present until late infancy, correct assessment of variant pathogenicity is fundamental for appropriate patients' management. Methods: Here, we analyzed three different computational methods, VEST3, REVEL and ClinPred, and after extracting predictions scores for 1585 NF1 missense variants listed in ClinVar, evaluated their performances and the score distribution throughout the neurofibromin protein. Results: For all the three methods, no significant differences were present between the scores of "likely benign", "benign", and "likely pathogenic", "pathogenic" variants that were consequently collapsed into a single category. The cutoff values for pathogenicity were significantly different for the three methods and among benign and pathogenic variants for all methods. After training five different models with a subset of benign and pathogenic variants, we could reclassify variants in three sharply separated categories. Conclusions: The recently developed metapredictors, which integrate information from multiple components, after gene-specific fine-tuning, could represent useful tools for variant interpretation, particularly in genetic diseases where a clinical diagnosis can be difficult.

Hints for Genetic and Clinical Differentiation of Adult-Onset Monogenic Autoinflammatory Diseases

Monogenic autoinflammatory diseases (mAIDs) are inherited errors of innate immunity characterized by systemic inflammation recurring with variable frequency and involving the skin, serosal membranes, synovial membranes, joints, the gastrointestinal tube, and/or the central nervous system, with reactive amyloidosis as a potential severe long-term consequence. Although individually uncommon, all mAIDs set up an emerging chapter of internal medicine: recent findings have modified our knowledge regarding mAID pathophysiology and clarified that protean inflammatory symptoms can be variably associated with periodic fevers, depicting multiple specific conditions which usually start in childhood, such as familial Mediterranean fever, tumor necrosis factor receptor-associated periodic syndrome, cryopyrin-associated periodic syndrome, and mevalonate kinase deficiency. There are no evidence-based studies to establish which potential genotype analysis is the most appropriate in adult patients with clinical phenotypes suggestive of mAIDs. This review discusses genetic and clinical hints for an ideal diagnostic approach to mAIDs in adult patients, as their early identification is essential to prompt effective treatment and improve quality of life, and also highlights the most recent developments in the diagnostic work-up for the most frequent hereditary periodic febrile syndromes worldwide.

The expanding pathways of autoinflammation: a lesson from the first 100 genes related to autoinflammatory manifestations

AutoInflammatory Diseases (AIDs) are a group of innate immune system disorders characterized by sterile inflammation without evidence of pathogenic autoantibodies or auto-reactive T lymphocytes. An expanding spectrum of genes and molecular pathways are associated with AIDs. Inflammasomopathies are secondary to dysregulation of multi-protein complexes, called inflammasomes, leading to an excessive maturation and secretion of IL1β and IL18. Patients present with persistent or recurrent systemic inflammation, abdominal and chest pain, skin rashes and are sensible to IL1 inhibitors. Unfolded proteins response causes a small number of AIDs that we propose to call immuno-proteinopathies, characterized by recurrent fevers and deep tissues inflammation. Other inflammatory conditions can occur in case of abnormalities of actin polymerization and the term of immuno-actinopathies is proposed. Generalized pustular psoriasis is a marker of autoinflammation mainly affecting the keratinocytes. Specific treatment targeting the p40 subunit of IL12 and IL23 or IL-17 are usually effective. Granulomatous inflammation characterizes AIDs related to NOD2 signaling defects. Defects in the ubiquitin-proteasome system cause a group of relopathies and some interferonopathies related to defect of the proteasome function (CANDLE syndrome). Gain of function of proteins regulating the production of type I interferons lead to severe inflammatory conditions, called interferonopathies. The JAK/STAT inhibitors are usually effective in these latter conditions. In conclusions, the identification of the main intracellular pathways involved in rare monogenic AIDs allows not only the proper classification of different conditions, but also highlight a pivotal role of possible novel therapeutic targets for the future.