Familial Mediterranean Fever Phenotype Research Articles

MEFV gene mutation spectrum in patients with familial mediterranean fever

MEFV gene mutation spectrum in patients with familial mediterranean fever

Investigation of Neutrophil Extracellular Trap (NET) Induction in Patients with Chronic Idiopathic Neutropenia Bearing Mutations in the Mediterranean Fever (MEFV) Gene

Introduction: Chronic idiopathic neutropenia (CIN) is a disorder characterized by the prolonged and unexplained reduction in the number of circulating neutrophils. The pathophysiology of CIN has been associated with an inflammatory bone marrow microenvironment consisting of activated T-cells with an oligoclonal/monoclonal profile and intermediate CD14bright/CD16+ monocytes that induce the apoptotic death of the granulocytic progenitor cells. To probe further the basis of immune cell activation in CIN we have recently investigated by next generation sequencing (NGS) the frequency of mutations in the MEFV gene encoding pyrin, in a cohort of 50 CIN patients without any signs/symptoms of Familial Mediterranean Fever (FMF). We have found that 9/50 patients displayed variants associated with typical or atypical FMF phenotype in the Greek population implicating exon 10 and/or exon 2 (Skendros P et al. Blood, 138, Sup.1, p3124;2021). Aim:MEFV mutations have been associated with increased neutrophil activation in FMF and other inflammatory diseases, neutrophil entry in autophagy and extrusion of Neutrophil Extracellular Traps (NETs) decorated with the pro-inflammatory cytokine IL-1β. The aim of the current study is to investigate the association between MEFV mutations and NET formation in neutrophils of CIN patients. Patients-Methods: We studied 20 CIN patients (17 females and 3 males) aged 27 to 78 years. Six CIN patients harbored at least one MEFV mutation with potential clinical significance (A744S homo/R202Q homo, I720M hetero, R202Q homo, K965R hetero, A744S hetero, M694V hetero) and 14 were negative for MEFV pathogenic mutations. The MEFV R202Q mutation is located in exon 2 whereas all the rest mutations are located in exon 10. We isolated neutrophils from healthy subjects (n=5), age- and sex- matched with the patients, and co-cultured them with serum from CIN patients. We used the supernatants of the cultures to quantify NETs with Sytox green staining for extracellular DNA and/or ELISA for dsDNA/MPO complexes. We also used the serum-treated neutrophils for the evaluation of NETosis by immunostaining using confocal microscopy. In addition, neutrophils isolated from CIN patients were used to detect their direct response to spontaneous NETosis induction. Statistical analysis was performed with one-way ANOVA adjusting for multiple comparisons. Results: By co-culturing patients' sera with healthy neutrophils obtained from five different healthy donors, we did not identify statistically significant differences in NETosis evaluation between the three study groups i.e. CIN patients with MEFV mutations, CIN patients negative for pathogenic MEFV mutations, and healthy individuals. On an individual basis, the patient harboring the double homozygous MEFV mutations (A744S/R202Q) displayed increased NETosis in immunostaining, Sytox and ELISA evaluation, as compared to MEFV unmutated CIN patients and healthy individuals. In addition, ex vivo culture of patients' neutrophils and microscopic observation gave us the indication that CIN patients, regardless of their MEFV gene variants, present increased NETosis compared to healthy individuals, suggesting an overactivation status of neutrophils in CIN. Conclusions: The neutrophils of CIN patients display increased NETosis irrespectively of the MEFV mutation status and may thus contribute to the inflammatory processes associated with the disease, a field that has not been investigated so far. Although in our study MEFV mutations did not appear to contribute significantly to inflammatory processes through the NETosis mechanism in CIN patients, their involvement in other aspects of immune deregulation such as through the mTOR/autophagy pathway remains to be further explored.

AN ATYPICAL PRESENTATION OF FAMILIAL MEDITERRANEAN FEVER

<h3>Introduction</h3> Familial Mediterranean Fever(FMF) is thought to be autosomal recessive disease characterized by periodic fevers associated with serositis. In this case we present a patient with FMF with only one mutation in MEFV gene, suggesting a more variable penetrance of the FMF phenotype. <h3>Case Description</h3> An 8-year-old female diagnosed with juvenile idiopathic arthritis and asymptomatic hematuria presented for elevated immunoglobulins and inflammatory markers. She had no history of recurrent/severe infections or fevers. She endorsed monoarticular joint pains and abdominal pains. Family history was significant for a 1-year-old sister diagnosed with PFAPA and a 15-months-old brother who died from human metapneumovirus associated pulmonary hemorrhage. On exam, she appeared well-nourished, no rash/oral ulcers/abdominal tenderness. Labs were significant for CRP-54, ESR-52, IgG-1950, IgA-327, IgM-230. Urinalysis had 3+ blood without proteinuria. Taken together, her history raised concern for monogenic inborn error of immunity and a primary immunodeficiency panel was sent. Her panel revealed a heterozygous pathogenic variance of MEFV(V726A) responsible for FMF. Her father was later also diagnosed with FMF responsive to colchicine with the same pathogenic MEFV variant. Her cytokines were elevated, including IL-1B, and she was subsequently started on colchicine 0.6mg BID and canakinumab 75mg q4-weeks. Following treatment, she had normalization of inflammatory markers (Table 1) and resolution of joint pains. <h3>Discussion</h3> This case highlights the existence of a subset of FMF patients who have only one mutation in the MEFV gene. Broadening our understanding of the complex genetics and variable penetrance of FMF can prevent delays in diagnosis and treatment.

Autoinflammatory syndromes with coexisting variants in Mediterranean FeVer and other genes: Utility of multiple gene screening and the possible impact of gene dosage

ObjectiveTo assess the possible impact conferred by co-existing variants in MEditerranean FeVer (MEFV) and other genes on systemic autoinflammatory disease (SAID) phenotype. MethodsConsecutive patients (n = 42) who underwent screening for SAIDs by next generation sequencing (NGS) targeting 26 genes, and carried at least one MEFV gene variant, were retrospectively studied. A total of 63 MEFV gene variants mainly located in exon 10 (n = 29) and exon 2 (n = 19) were identified in 21 patients with juvenile- and 21 with adult-onset disease. ResultsThe candidate clinical diagnosis was Familial Mediterranean Fever (FMF) in 11, polygenic SAIDs (PFAPA, Still's disease, atypical SAPHO and inflammatory bowel disease) in 9, whereas the disease could not be clinically defined in 22 patients. Notably, 33 out of the 42 patients (79%) had at least one co-existing variants in 19 genes other than MEFV. NGS confirmed all clinical diagnoses and helped defining diagnosis in 59% of the remaining cases. Patients with undefined SAIDs (n = 9) or atypical FMF phenotype (n = 12) carried significantly more disease-causing variants in genes other than MEFV compared to patients with typical FMF (n = 9). More than one variants in these genes were significantly associated with adult-onset disease, while disease–causing variants in the same genes were also associated with an overall more severe SAID phenotype. ConclusionCo-existing variants in SAID-related genes may explain the phenotypic variability of these diseases. Further studies should validate combined molecular and clinical data in order to better understand the cumulative gene dosage effect and improve the classification of these patients.

Increased Frequency of Mutations in the Gene Responsible for Familial Mediterranean Fever (MEFV) in a Cohort of Patients with Chronic Idiopathic Neutropenia

▪Introduction-Aim: Chronic idiopathic neutropenia (CIN) is a neutrophil disorder characterized by the prolonged and unexplained reduction in the number of peripheral blood (PB) absolute neutrophil counts (ANC). The underlying pathogenesis in CIN implicates the production of proinflammatory cytokines by activated lymphocytes and monocytes that induce excessive apoptotic death of the bone marrow (BM) granulocytic progenitor cells. Clonal hematopoiesis identified by next generation sequencing (NGS) of myeloid genes is found in 11% of CIN patients conferring an increased risk for MDS/AML transformation whereas the non-clonal patients display usually a benign course. The basis for the immune cell activation and proinflammatory cytokine production in CIN remains obscure. Based on previously reported data showing increased frequency of mutations of the MEFV gene encoding pyrin in patients with idiopathic inflammatory conditions other than typical Familial Mediterranean Fever (FMF), we sought to investigate the common MEFV mutations in a cohort of well characterized CIN patients.Patients-Methods: We have studied 50 patients fulfilling the previously reported diagnostic criteria of CIN (median ANC 1.5x10 9/L, range 0.2-1.7 x10 9/L), 44 females and 6 males with a median age of 56 years (range 25-87 years) and a long-follow-up (median 132 months, range 8-336 months) in the Department of Hematology of the University Hospital of Heraklion, Crete, Greece. Nonisotopic RNase cleavage assay (NIRCA) analysis was used as first screening method to detect MEFV exons 10 and 2 mutations in DNA extracted from PB or BM samples from CIN patients, confirmed by direct NGS analysis. These sequences contain the main disease-related mutations and polymorphisms.Results: Genetics alterations of MEFV were detected in 22 out of 50 CIN patients (44%). Pathogenic mutations (variants associated with typical or “atypical” FMF phenotype in Greek population) were identified in 10/50 CIN patients (20%). The 20% frequency of MEFV mutations in exon 10 and/or exon 2 in CIN patients is significantly higher compared to the carrier rate of common MEFV mutations in the healthy Greek population (0.7%) according to our previously reported data (P<0.0001, Fisher's exact test). NGS analysis confirmed the mutational pattern of NIRCA and specifically showed: (a) one patient with heterozygous I720M (ATC>ATG; Ile>Met), two patients with heterozygous A744S (GCC>TCC; Ala>Ser) and one with homozygosity, one patient with heterozygous M694V (ATG>GTG; Met>Val), one with heterozygous K695R (AAG>AGG; Lys>Arg) and one with heterozygous M680I (ATG>ATC; Met>Ile), all in exon 10, and (b) four patients with homozygous R202Q mutation in exon 2 (one patient with homozygous A744S co-mutation in exon 10) and two patients with R202Q heterozygosity combined with heterozygosity of I720M and A744S of exons 10, respectively. None of the patients displayed any symptoms/signs of FMF or other systemic inflammatory disease. No statistically significant differences were identified between MEFV mutated and non-mutated CIN patients in the severity of neutropenia or in lymphocyte, monocyte, hemoglobin and platelet counts. A significant difference was identified between the two patient groups in serum IgG (1440±264 vs 1133±245 mg/dl; P = 0.0023, Mann-Whitney test) but not IgA or IgM levels.Discussion: This study reports for the first time that 20% of unselected, consecutive patients with CIN carry mutations of the MEFV gene without clinical manifestations of FMF. Whether these patients represent atypical cases of FMF or the identified MEFV genetic alterations have a pathogenetic/modifying effect in the inflammatory responses associated with CIN is an open/novel field of research. As a first step we are currently investigating the neutrophil autophagic status, IL-1β production and the neutrophil extracellular trap (NET) formation in CIN patients with mutations in MEFV to clarify their potential effect in the immune deregulation known to characterize CIN. DisclosuresNo relevant conflicts of interest to declare.

MEFV E148Q variant is more associated with familial Mediterranean fever when combined with other non-exon 10 MEFV variants in Japanese patients with recurrent fever

Objective To investigate the genetic characteristics of one of the MEFV gene variants, p.Glu148Gln (E148Q), in patients with familial Mediterranean fever (FMF) and examine its significance in Japanese patients with recurrent fever. Methods The clinical phenotype and genomic variants of systemic autoinflammatory diseases (SAIDs), including MEFV, were analyzed in 211 Japanese patients with recurrent fever. Genetic analysis was performed via next-generation sequencing of exons, including exon-intron boundaries. Results Twelve patients met the diagnostic criteria for SAIDs other than FMF. Considering 199 patients with recurrent fever, 137 cases (68.8%) were clinically diagnosed with FMF. Although Bonferroni-adjusted p-value did not reach significance level, the group containing heterozygous E148Q and other variants tended to be at higher risk of developing the FMF phenotype (nominal p = .036) than the group with heterozygous E148Q only. Comparison between the group with heterozygous E148Q and other variants and the heterozygous group containing non-E148Q showed no statistically significant difference in FMF phenotype expression (nominal p = 1.00). Conclusion Patients with heterozygous E148Q and other variants exhibited higher expression of FMF phenotype than those with heterozygous E148Q only, and suggested that other variants than E148Q as well as exon 10 variants might contribute to the FMF phenotype.

Phenotypic characterization of Familial Mediterranean Fever patients harboring variants of uncertain significance

Background/aimFamilial Mediterranean Fever (FMF) is the prototype of hereditary autoinflammatory disorders and caused by mutations on the MEFV gene located on the short arm of chromosome 16. Although some MEFV variants are clearly associated with disease phenotype, there are numerous variants with unknown clinical association which are termed as variants of uncertain significance (VUS). Here, we present clinical correlations of VUS in a large cohort of adult FMF patients from three tertiary centers located in Central Anatolia.Materials and methodsAll patients were recruited from FMF in Central Anatolia (FiCA) cohort. Demographic (sex, age at disease onset) and clinical features (disease characteristics, attack frequency, mean colchicine dose, colchicine nonresponsiveness, amyloidosis, and persistent inflammation) of patients with VUS were compared with those harboring pathogenic variants. Disease severity and damage were also evaluated using international severity score for FMF (ISSF) and autoinflammatory disease damage index (ADDI), respectively.ResultsAmong 971 participants included, MEFV gene analysis results were available for 814 patients. Twenty-six (3.2%) patients had single heterozygous VUS and 54 (6.6%) had pathogenic/VUS complex heterozygous variants. Patients with single heterozygous VUS had similar demographic/clinical features, ISSF and ADDI scores compared to those with single heterozygous pathogenic variant (p > 0.05 for all). No difference was observed in the demographic and clinical features of patients with single heterozygous pathogenic mutation and pathogenic/VUS complex heterozygous variant (p > 0.05 for all). ISSF and ADDI scores were lower in pathogenic/VUS complex heterozygous patients than those harboring single pathogenic mutation (p = 0.006 and 0.004, respectively).ConclusionOur findings suggest that patients with single heterozygous VUS has mild FMF phenotype similar to those with single pathogenic mutation. Pathogenic/VUS complex heterozygosity does not lead to a more severe clinical phenotype than having a single pathogenic variant.

M680I/M694V Heterozygous Mutation in Early Onset Familial Mediterranean Fever

Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disorder affecting individuals with biallelic pathogenic mutations in the MEFV gene. The disease is characterized by recurrent attacks of fever and serosal inflammation as manifested by abdominal and chest pain. This case report presents an FMF case with a 3-year history of pain crises consisting of severe abdominal pain and fever, lasting up to 72 h. Genetic investigation identified an uncommon heterozygous mutation in the MEFV gene. This mutation is associated with a more severe phenotype of FMF and may lead to an early onset of the disease.

The importance of Mediterranean fever gene in familial Mediterranean fever.

Familial Mediterranean fever (FMF) is the most common autoinflammatory disease characterized by recurrent serositis attacks and fever. The discovery of the Mediterranean fever (MEFV) gene has been a milestone in FMF etiopathogenesis. Our knowledge about the relationship between the MEFV gene and FMF phenotype increases each day. This study aims to investigate the relationship between MEFV gene mutations and the FMF clinical findings of a single-center FMF cohort. Gender, age, age at symptom onset, age at diagnosis, clinical characteristics, and MEFV gene analysis of the patients were recorded. A total of 837 FMF patients were included in this study. There were 515 females and 322 males. The age at symptom onset was 18.3±10.9 years, while the age at diagnosis was 24.4±10.9 years. The most common symptom that accompanied fever was peritonitis (91.1%), while the other common clinical findings were pleuritis (45%), myalgia (44%), and arthritis (36%). A total of 47 patients developed amyloidosis. A total of 553 (66%) FMF patients had M694V mutation, 221 (26%) of which were homozygous, while 332 (40%) were heterozygous. Exon 10 mutation frequency was 759 (91%), while the non-exon 10 mutation frequency was 78 (9%). There was no wild type among the patients. In conclusion, the fact that a vast majority of the disease burden was constituted by the exon 10, especially M694V mutations and that none of the 837 patients from our cohort had a wild-type FMF proved the significance of MEFV gene mutation analysis. Therefore, we speculate that it is necessary to examine the MEFV gene mutations in each FMF suspected case. It seems plausible to re-evaluate the FMF diagnosis for cases in which a wild type MEFV gene mutation occurs.

Enthesitis may be one of the signs of severe disease in familial Mediterranean fever.

Familial Mediterranean fever (FMF) is an auto-inflammatory disease that is also characterized with some of the common musculoskeletal features of spondyloarthritis (SpA). Enthesitis is the hallmark of SpA. Recently, it was postulated that exertional leg pain is a possible sign of lower extremity enthesitis associated with FMF severity. In this study, we have evaluated the association between the enthesitis, enthesitis score and disease severity in FMF patients. We enrolled 238 FMF patients that fulfilled the modified Tel-Hashomer criteria. We assessed the presence of enthesitis at the Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) defined sites with standard palpation method. Then, FMF patients dichotomised two groups as enthesitis group and controls. Herein, we evaluated the enthesis extensity with MASES. FMF disease severity was determined via the international severity scoring system for FMF (ISSF). Firstly, we have compared demographic properties, disease-related features and ISSF scores of the groups. Then, we have correlated ISSF with MASES in enthesitis group. We showed that 54 (22.6%) of 238 patients had enthesitis. The demographic features were similar between the groups. The enthesitis group had higher ISSF scores (p < 0.001); higher frequency of fever (p = 0.004), exertional leg pain (p < 0.001), myalgia (p < 0.001) and arthritis (p = 0.01); and more intense, widespread, frequent and longer attacks compared with controls. Moreover, there was a weak correlation between ISSF and MASES in the patients with enthesitis. Enthesitis may be a sign of more severe FMF phenotype and frequently associated with other musculoskeletal manifestations resemble SpA. Key points •More than one-fifth of the patients with FMF would suffer from enthesitis. •The FMF patients with enthesitis had higher ISSF scores; higher frequency of fever, exertional leg pain, myalgia and arthritis; and more intense, widespread, frequent and longer attacks as compared with controls. •Enthesitis may be a sign of more severe FMF phenotype and frequently associated with other SpA-like musculoskeletal feature.

FAMILIAL MEDITERRANEAN FEVER: ASSESSING THE OVERALL CLINICAL IMPACT AND FORMULATING TREATMENT PLANS

Recurrent self-limited attacks of fever and short-lived inflammation in the serosal membranes, joints, and skin are the leading features of familial Mediterranean fever (FMF), the most common autoinflammatory disorder in the world, transmitted as autosomal recessive trait caused by MEFV gene mutations. Their consequence is an abnormal function of pyrin, a natural repressor of inflammation, apoptosis, and release of cytokines. FMF-related mutant pyrins are hypophosphorylated following RhoA GTPases’ impaired activity and show a propensity to relapsing uncontrolled systemic inflammation with inappropriate response to inflammatory stimuli and leukocyte spread to serosal membranes, joints or skin. Typical FMF phenotype 1 consists of brief episodes of inflammation and serositis, synovitis, and/or erysipelas-like eruption, whereas phenotype 2 is defined by reactive amyloid-associated (AA) amyloidosis, which is the most ominous complication of FMF, in otherwise asymptomatic individuals.Furthermore, FMF phenotype 3 is referred to the presence of two MEFV mutations with neither clinical signs of FMF nor AA amyloidosis. The influence of epigenetic and/or environmental factors can contribute to the variable penetrance and phenotypic heterogeneity of FMF. Colchicine, a tricyclic alkaloid with anti-microtubule and anti-inflammatory properties, is the bedrock of FMF management: daily administration of colchicine prevents the recurrence of FMF attacks and the development of secondary AA amyloidosis. Many recent studies have also shown that anti-interleukin-1 treatment is the best therapeutic option for FMF patients nonresponsive or intolerant to colchicine. This review aims to catch readers’ attention to the clinical diversity of phenotypes, differential diagnosis, and management of patients with FMF.

Correlation of Secretory Activity of Neutrophils With Genotype in Patients With Familial Mediterranean Fever.

Familial Mediterranean fever (FMF) is an autoinflammatory disorder caused by pyrin-encoding MEFV mutations. Patients present with recurrent but self-limiting episodes of acute inflammation and often have persistent subclinical inflammation. The pathophysiology is only partially understood, but neutrophil overactivation is a hallmark of the disease. S100A12 is a neutrophil-derived proinflammatory danger signal that is strongly elevated in active FMF. This study was undertaken to characterize the secretory activity of neutrophils in vitro and investigate the association of S100A12 with disease activity and genotype in patients with FMF. Neutrophils from FMF patients carrying the p.M694V mutation (1 compound heterozygous and 5 homozygous) and neutrophils from 4 healthy control subjects were purified and stimulated in vitro. Neutrophil secretion of S100A12, interleukin-18 (IL-18), IL-1β, and caspase 1 was determined. Based on these in vitro analyses, serum concentrations of S100A12, IL-18, and IL-1β were also analyzed in 128 clinically and genetically characterized patients with FMF. In vitro, unstimulated neutrophils from p.M694V-positive patients spontaneously secreted more S100A12, IL-18, and caspase 1 compared to neutrophils from healthy controls. Serum concentrations of S100A12 correlated with disease activity and genotype, with the levels being highest in homozygous patients and with compound heterozygotes displaying higher levels than heterozygotes. Compared to individuals negative for the p.M694V mutation, heterozygous, compound heterozygous, or homozygous p.M694V-positive patients had higher serum levels of S100A12 and IL-18 during inactive and subclinical disease. The FMF phenotype is known to be more severe in patients carrying the p.M694V mutation. This report describes 2 molecules secreted by unconventional secretory pathways, S100A12 and IL-18, whose concentrations correlated with clinical disease activity and genotype in patients with FMF. In this clinically and genetically heterogeneous disease, management of these surrogate markers might help to improve patient care and outcomes.

Discontinuing colchicine in symptomatic carriers for MEFV (Mediterranean FeVer) variants.

Familial Mediterranean fever (FMF) is inherited autosomal recessively; however, heterozygotes may express FMF phenotype. We aimed to define the characteristics of FMF patients heterozygous for MEFV (MEditerranean FeVer) mutations in whom colchicine was stopped after a period of treatment, with close follow-up. We reviewed the charts of 182 children who were heterozygous for MEFV variants. We excluded the patients (n = 34) heterozygous for MEFV variants of unknown significance and patients with typical periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis syndrome (n = 2). All patients were followed up with their routine analysis and serum amyloid A levels every 6months while on colchicine treatment and every 3-6months thereafter. MEFV gene variant analysis was performed with Sanger sequencing. Twenty-two out of 146 heterozygotes initially had FMF phenotype, but colchicine was discontinued after a treatment period. The most common MEFV variant was M694V (86.3%). The median age at diagnosis/initiation of colchicine was 76 (24-144) months. The median duration of colchicine treatment was 36 (24-110) months. The median age at colchicine cessation was 120 (55-172) months. At the time of colchicine cessation, the median attack- and inflammation-free period was 27 (24-84) months. The median follow-up after colchicine cessation was 22.5 (6-102) months. We re-started colchicine in only two patients because of recurrence of symptoms. Individuals with one mutation only can display FMF phenotype and require colchicine for the clinical and laboratory inflammation. However, in some of these patients, colchicine may be discontinued with very careful follow-up.

Familial Mediterranean fever is no longer a rare disease in Japan.

BackgroundThe aim of this study was to evaluate the clinical manifestations and prevalence of familial Mediterranean fever (FMF) in Japanese patients with unexplained fever and rheumatic manifestations.MethodsWe enrolled 601 patients with unexplained fever or suspected FMF throughout Japan between 2009 and 2015. Patients were divided into three groups according to Tel Hashomer criteria: sure FMF, probable FMF, and non-FMF patients, including definitive rheumatic diseases. Mutation detection in exons 1, 2, 3, and 10 of the FMF gene MEFV was performed by direct sequencing.ResultsA total of 192 patients (31.9 %) were diagnosed with FMF according to FMF diagnostic criteria. These could be divided into sure FMF (56.3 %, n = 108) and probable FMF (43.7 %, n = 84) patients. Fever, abdominal symptoms, and thoracic symptoms were significantly more common in FMF than non-FMF patients. Among FMF patients, 26 (13.5 %) had concomitant rheumatic diseases. Most FMF patients (94.3 %, 181/192) carried at least one MEFV mutation. Allele frequencies of M694I (13.5 % vs 0 %) and E148Q (39.1 % vs 24.8 %) mutations were significantly higher in FMF compared with healthy subjects. Allele frequencies of common MEFV mutations in FMF patients were M694I (13.5 %), P369S (8.6 %), R408Q (8.1 %), G304R (2.9 %), R202Q (4.4 %), E148Q (39.1 %), L110P (11.7 %), and E84K (3.1 %). Patients with a sure FMF phenotype had a higher frequency of MEFV exon 10 mutation (M694I) and a lower frequency of MEFV exon 3 mutations (P369S, R408Q) compared with those with a probable FMF phenotype.ConclusionThe high prevalence of FMF in Japanese patients with unexplained fever was confirmed in the present study. FMF should be suspected in cases of unexplained fever or non-specific rheumatic manifestations, and mutational analysis of MEFV could be useful to predict the clinical phenotypes of FMF in Japan.

Generation of integration-free induced pluripotent stem cells from a patient with Familial Mediterranean Fever (FMF)

Fibroblasts from a Familial Mediterranean Fever (FMF) patient were reprogrammed with episomal vectors by using the Neon Transfection System for the generation of integration-free induced pluripotent stem cells (iPSCs). The resulting iPSC line was characterized to determine the expression of pluripotency markers, proper differentiation into three germ layers, the presence of normal chromosomal structures as well as the lack of genomic integration. A homozygous missense mutation in the MEFV gene (p.Met694Val), which lead to typical FMF phenotype, was shown to be present in the generated iPSC line.

Molecular modeling of complete tertiary structure of pyrin and influence of mutations on it

Pyrin protein is the product of the MEFV gene, mutations in which cause the manifestation of Familial Mediterranean Fever (FMF). Complete tertiary structure of pyrin and the effects of mutations on it are still experimentally not studied. Mutations - E148Q, M680I, M694V, M694I, V726A, A744S and R761H of pyrin induce manifestation of the most widespread and severe forms of FMF. One striking feature of FMF is the phenomenon of complex allele mutations. In case of complex allele mutations, the pyrin protein will contain more than one mutated amino acids. From currently known complex allele mutations there are those that combine the most widespread and severe single mutations - M680I-M694I, E148Q-M694V, E148Q-M694I, E148Q-V726A, E148Q-A744S, E148Q-R761H, E148Q-V726A-R761H. In complex alleles, one mutation may have a modifying effect on the other one. The other striking feature of FMF is the fact that despite the fact that the FMF is considered as an autosomal recessive autoinflammatory syndrome, were detected mutations - T577N и T577S for which was proved autosomal dominant inheritance. Understanding the correlation between the FMF phenotype and genotype is further obscured by the existence of complex allele and dominant mutations. Therefore, we suggest that computational modeling of native and mutated pyrin complete tertiary structure and their comparative investigation will help to understand the effects of abovementioned mutations on pyrin and on FMF manifestation in general.

Familial Mediterranean fever without MEFV mutations: a case-control study.

BackgroundAlthough familial Mediterranean fever (FMF) was originally defined as an autosomal recessive disorder, approximately 10–20% of FMF patients do not carry any FMF gene (MEFV) mutations. Fine phenotype characterization may facilitate the elucidation of the genetic background of the so called “FMF without MEFV mutations”. In this study we clinically and demographically characterize this subset.MethodsMEFV mutation-negative FMF and control patients were recruited randomly from a cohort followed in a dedicated FMF clinic. The control subjects comprised 2 groups: 1. typical population of FMF, consisting of genetically heterogeneous patients manifesting the classical spectrum of FMF phenotype and 2. a severe phenotype of FMF, consisting of FMF patients homozygous for the p.M694V mutation.ResultsForty-seven genetic-negative, 60 genetically heterogeneous and 57 p.M694V homozygous FMF patients were enrolled to the study. MEFV-mutation negative FMF patients showed a phenotype closely resembling that of the other 2 populations. It differed however from the p.M694V homozygous subset by its milder severity (using Mor et al. scoring method), as determined by the lower proportion of patients with chest and erysipelas like attacks, lower frequency of some of the chronic manifestations, lower colchicine dose and older age of disease onset.ConclusionsMEFV mutation-negative FMF by virtue of its classical FMF phenotype is probably associated with a genetic defect upstream or downstream to MEFV related metabolic pathway.

The spectrum of MEFV gene mutations and genotypes in Van province, the eastern region of Turkey, and report of a novel mutation (R361T)

Familial Mediterranean fever (FMF) is the most common hereditary inflammatory periodic disease, characterized by recurrent episodes of fever and abdominal pain, synovitis, and pleuritis. The aim of this study was to determine the frequency and distribution of Mediterranean fever (MEFV) gene mutations in Van province of Eastern Anatolia and to compare them with the other studies from various regions of Turkey. Therefore, we retrospectively evaluated MEFV gene mutations in 1058 pediatric patients with suspected FMF. The MEFV gene mutations were investigated using Sanger sequencing and the multiplex minisequencing technique. We identified 37 different genotypes and 16 different mutations. The four most common mutations and allelic frequencies were M694V (36.50%), E148Q (32.77%), V726A (14.09%), and M694I (4.41%). M694V was the most common mutation, and the M694I frequency was found to be higher compared to studies from other regions of Turkey. In addition, we identified a novel missense mutation (R361T, c.1082G>C) in exon 3 of the MEFV gene in a 12-year-old boy, who had a typical FMF phenotype. In conclusion, this study evaluated the distribution of MEFV gene mutations in children with FMF as the first study conducted in Van province, Eastern Anatolia.

Familial Mediterranean fever in children from the Aegean region of Turkey:gene mutation frequencies and phenotype–genotype correlation

Familial Mediterranean fever (FMF) is diagnosed by fever episodes with sterile peritonitis, arthritis, pleurisy, and erysipelas-like erythema. The relationship between phenotype and genotype in FMF has not been adequately explained. The aim of this study was to characterize the phenotype and genotype correlation in FMF. Clinical diagnosis of FMF was conducted according to the Tel Hashomer criteria. Pras scoring was used to determine clinical severity. FMF strip assay analysis was used, and the hotspot regions were observed with PCR amplification and automatic DNA sequence analysis method. We showed commonly seen mutations (most frequently M694V) in a study group of 191 patients. The disease severity score of patients with M694V mutation was high on the Pras scoring system. Patients with M694V mutation needed high colchicine dosages to control disease activity. R202Q was the most commonly seen polymorphism in 70 patients. The coexpression of R314R single nucleotide polymorphism on third exon was shown in our study. Moreover, D102D, G138G, and A165A subhaplotypes and E474E, Q476Q, and D510D subhaplotypes were also shown. DNA sequence analysis should be a commonly used method for progress in the field of molecular genetics and for the better understanding of the FMF phenotype and genotype relationships in all populations.

Familial Mediterranean Fever

Familial Mediterranean fever (FMF) is an autoinflammatory disease caused by MEditerranean FeVer gene (MEFV) mutations. In Japan, patients with FMF have been previously reported, including a mild or incomplete form. Several factors are presumed to contribute to the variable penetrance and to the phenotypic variability of FMF. We conducted the current study to investigate the correlation of variable clinical presentations and MEFV genotypic distributions in Japanese FMF patients.We analyzed demographic, clinical, and genetic data for 311 FMF patients enrolled in the study. Clinically, we classified FMF into 2 phenotypes: 1) the “typical” form of FMF, and 2) the “atypical” form of FMF according to the Tel Hashomer criteria. Patients with the typical FMF phenotype had a higher frequency of febrile episodes, a shorter duration of febrile attacks, more frequent thoracic pain, abdominal pain, a family history of FMF, and MEFV exon 10 mutations. Conversely, patients with the atypical FMF phenotype had a lower frequency of fever episodes and more frequent arthritis in atypical distribution, myalgia, and MEFV exon 3 mutations. Multivariate analysis showed that the variable associated with typical FMF presentation was the presence of MEFV exon 10 mutations. Typical FMF phenotype frequencies were decreased in patients carrying 2 or a single low-penetrance mutations compared with those carrying 2 or a single high-penetrance mutations (M694I), with an opposite trend for the atypical FMF phenotype. In addition, patients having more than 2 MEFV mutations had a younger disease onset and a higher prevalence of thoracic pain than those carrying a single or no mutations. Thus, MEFV exon 10 mutations are associated with the more typical FMF phenotype. In contrast, more than half of the Japanese FMF patients without MEFV exon 10 mutations presented with an atypical FMF phenotype, indicating that Japanese FMF patients tend to be divided into 2 phenotypes by a variation of MEFV mutations.