Familial Mediterranean fever among patients from Karabakh and the diagnostic value of MEFV gene analysis in all classically affected populations

miRNAs as attractive diagnostic and therapeutic targets for Familial Mediterranean Fever

Familial Mediterranean Fever (FMF) is a hereditary early-onset disease that causes periodical fever attack, excessive release of IL-1β, serositis, arthritis and peritonitis. Genetic analyses conducted on FMF patients (mutated and non-mutated) have highlighted that additional contributing factors such as epigenetics and environment play a role in clinical manifestations of FMF. Recently researchers report that microRNAs (miRNAs), implicated in epigenetic mechanisms, may contribute to the pathogenesis of FMF. miRNAs, a member of the captivating noncoding RNA family, are the single-strand transcripts that work in physiological and pathophysiological processes by regulating target gene expression. Recent studies have shown that miRNAs are associated with various mechanisms involved in the pathogenesis of FMF, such as apoptosis, inflammation and autophagy. Moreover, these miRNAs molecules might have potential use in treatment, therapeutic response monitoring and the diagnosis of subtypes of the disease in the future. Motivated by these potential benefits (diagnostic and therapeutic) of miRNAs, we focus on recent advances of clinical significances and potential action mechanisms of miRNAs in FMF pathogenesis and discuss their potential use for FMF.

Coexistence of familial Mediterranean fever and Behçet's disease: a case report

Behçet's disease (BD) is a chronic, multi-systemic vasculitis, characterized by a triad of recurrent aphthous stomatitis, genital aphthae, and uveitis. It is common in the Eastern Mediterranean, Middle East, and Eastern Asian countries. Familial Mediterranean fever (FMF) is an autosomal recessive autoinflammatory disorder, which is common seen in the Turkish, Armenian, Arabic, and Sephardic Jewish populations. It is characterized by recurrent episodes of fever, peritonitis, pleuritis, arthritis, and erysipelas-like skin lesions. Behçet's disease and FMF have common clinical features and geographic distribution. Herein, we present a 19-year-old female patient with coexistence of FMF and BD in the light of literature data.

Familial Mediterranean Fever: Recent Developments in Pathogenesis and New Recommendations for Management

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease (AID) affecting mainly the ethnic groups originating from Mediterranean basin. The disease is characterized by self-limited inflammatory attacks of fever and polyserositis along with elevated acute phase reactants. FMF is inherited autosomal recessively; however, a significant proportion of heterozygotes also express the phenotype. FMF is caused by mutations in the MEFV gene coding for pyrin, which is a component of inflammasome functioning in inflammatory response and production of interleukin-1β (IL-1β). Recent studies have shown that pyrin recognizes bacterial modifications in Rho GTPases, which results in inflammasome activation and increase in IL-1β. Pyrin does not directly recognize Rho modification but probably affected by Rho effector kinase, which is a downstream event in the actin cytoskeleton pathway. Recently, an international group of experts has published the recommendations for the management of FMF. Colchicine is the mainstay of FMF treatment, and its regular use prevents attacks and controls subclinical inflammation in the majority of patients. Furthermore, it decreases the long-term risk of amyloidosis. However, a minority of FMF patients fail to response or tolerate colchicine treatment. Anti-interleukin-1 drugs could be considered in these patients. One should keep in mind the possibility of non-compliance in colchicine-non-responders. Although FMF is a relatively well-described AID and almost 20 years has passed since the discovery of the MEFV gene, there are still a number of unsolved problems about it such as the exact mechanism of the disease, symptomatic heterozygotes and their treatment, and the optimal management of colchicine resistance.

Unified Modeling of Familial Mediterranean Fever and Cryopyrin Associated Periodic Syndromes

Familial mediterranean fever (FMF) and Cryopyrin associated periodic syndromes (CAPS) are two prototypical hereditary autoinflammatory diseases, characterized by recurrent episodes of fever and inflammation as a result of mutations in MEFV and NLRP3 genes encoding Pyrin and Cryopyrin proteins, respectively. Pyrin and Cryopyrin play key roles in the multiprotein inflammasome complex assembly, which regulates activity of an enzyme, Caspase 1, and its target cytokine, IL-1β. Overproduction of IL-1β by Caspase 1 is the main cause of episodic fever and inflammatory findings in FMF and CAPS. We present a unifying dynamical model for FMF and CAPS in the form of coupled nonlinear ordinary differential equations. The model is composed of two subsystems, which capture the interactions and dynamics of the key molecular players and the insults on the immune system. One of the subsystems, which contains a coupled positive-negative feedback motif, captures the dynamics of inflammation formation and regulation. We perform a comprehensive bifurcation analysis of the model and show that it exhibits three modes, capturing the Healthy, FMF, and CAPS cases. The mutations in Pyrin and Cryopyrin are reflected in the values of three parameters in the model. We present extensive simulation results for the model that match clinical observations.

The myths we believed in familial Mediterranean fever: what have we learned in the past years?

Familial Mediterranean fever is the most common monogenic periodic fever syndrome over the world especially in the eastern Mediterranean. It presents with recurrent and self-limited inflammatory attacks of fever and polyserositis along with high acute-phase reactants. The disease is associated with mutations in the MEFV gene that encodes pyrin, a component of inflammasome, which leads to exaggerated inflammatory response through uncontrolled production of interleukin 1. With the identification of the gene associated with the disease, we believed that everything was solved and that this was an ordinary monogenic disease with autosomal recessive inheritance. However, through the breathtaking progress in the basic research field as well as the clinical care of these patients, we have understood that the picture for this monogenic disorder was more complicated than we had anticipated. In this review, we have discussed the myths we believed in familial Mediterranean fever and how they have evolved during the past years.

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

Background

Although 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.

Methods

MEFV 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.

Results

Forty-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.

Conclusions

MEFV 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.

Untangling the web of systemic autoinflammatory diseases

The innate immune system is involved in the pathophysiology of systemic autoinflammatory diseases (SAIDs), an enlarging group of disorders caused by dysregulated production of proinflammatory cytokines, such as interleukin-1β and tumor necrosis factor-α, in which autoreactive T-lymphocytes and autoantibodies are indeed absent. A widely deranged innate immunity leads to overactivity of proinflammatory cytokines and subsequent multisite inflammatory symptoms depicting various conditions, such as hereditary periodic fevers, granulomatous disorders, and pyogenic diseases, collectively described in this review. Further research should enhance our understanding of the genetics behind SAIDs, unearth triggers of inflammatory attacks, and result in improvement for their diagnosis and treatment.

The risk of familial Mediterranean fever in MEFV heterozygotes: a statistical approach

Background

Familial Mediterranean fever (FMF) is an autosomal recessive autoinflammatory disorder due to MEFV mutations and one of the most frequent Mediterranean genetic diseases. The observation of many heterozygous patients in whom a second mutated allele was excluded led to the proposal that heterozygosity could be causal. However, heterozygosity might be coincidental in many patients due to the very high rate of mutations in Mediterranean populations.

Objective

To better delineate the pathogenicity of heterozygosity in order to improve genetic counselling and disease management.

Methods

Complementary statistical approaches were used: estimation of FMF prevalence at population levels, genotype comparison in siblings from 63 familial forms, and genotype study in 557 patients from four Mediterranean populations.

Results

At the population level, we did not observe any contribution of heterozygosity to disease prevalence. In affected siblings of patients carrying two MEFV mutations, 92% carry two mutated alleles, whereas 4% are heterozygous with typical FMF diagnosis. We demonstrated statistically that patients are more likely to be heterozygous than healthy individuals, as shown by the higher ratio heterozygous carriers/non carriers in patients (p<10⁻⁷–p<0.003). The risk for heterozygotes to develop FMF was estimated between 2.1×10⁻³ and 5.8×10⁻³ and the relative risk, as compared to non carriers, between 6.3 and 8.1.

Conclusions

This is the first statistical demonstration that heterozygosity is not responsible for classical Mendelian FMF per se, but constitutes a susceptibility factor for clinically-similar multifactorial forms of the disease. We also provide a first estimate of the risk for heterozygotes to develop FMF.

Unexplained recurrent fever: when is autoinflammation the explanation?

Recurrent fever can be the sole or leading manifestation of a variety of diseases including malignancies, autoimmune diseases and infections. Because the differential diagnoses are manifold, no formal guidelines for the approach of patients with recurrent fever exists. The newly recognized group of autoinflammatory diseases are often accompanied by repetitive fever attacks. As these episodes are frequently associated by a variety of divergent presentations, the differentiation of other causes for febrile illnesses can be difficult. In this article, we first review disease entities, which frequently present with the symptom of recurrent fever. In a next step, we summarize their characteristic pattern of disease presentation. Finally, we analyse key features of autoinflammatory diseases, which are helpful to distinguish this group of diseases from the other causes of recurrent fever. Recognizing these symptom patterns can provide the crucial clues and, thus, lead to the initiation of targeted specific diagnostic tests and therapies.

Triggers for attacks in familial Mediterranean fever: application of the case-crossover design

The etiology of recurrent attacks of serositis in familial Mediterranean fever (FMF) is not completely understood. Uncontrolled clinical case series have reported that factors associated with emotional, physiological, or physical stress precede and might trigger the attacks. This case-crossover study, conducted between July 2007 and May 2008, aimed to estimate the role of precipitating factors in attacks in a sample of Armenian FMF patients in Yerevan, Armenia, where 104 patients contributed 55 case and 189 control time periods. The authors used conditional logistic regression to compare frequency of exposure to stressful events, strenuous physical activity, menstrual periods, and high-fat food consumption prior to FMF attacks and on attack-free random days. Multiple stressful life events predicted FMF attacks 2 days following the event. After adjustment for treatment, an additional stressful event was associated with an estimated 70% increase in the odds of having an FMF attack on the second day (95% confidence interval: 1.04, 2.79). High levels of perceived stress were also associated with FMF attacks. Physical exertion and high-fat diet did not increase the likelihood of FMF attacks. The possibility of prevention of attacks in FMF needs to be tested through stress-reduction interventions.

Familial Mediterranean fever gene (MEFV) mutations as a modifier of systemic lupus erythematosus

The objective of this study was to assess the prevalence of the Mediterranean FeVer ( MEFV) gene mutations in systemic lupus erythematosus (SLE) patients and their effect on organ involvement, as well as disease activity and severity. The frequencies of three familial Mediterranean fever-related MEFV gene mutations ( M694V, V726A and E148Q) were investigated in 70 SLE patients. Organ involvement, Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage index and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores were correlated with mutation carriage. Eleven of 70 patients (15.7%) were found to carry an MEFV mutation. A single patient harbored two mutations, E148Q and V726A, without overt familial Mediterranean fever while the rest were heterozygous carriers. Four of the 11 carried an M694V mutation, four carried V726A and two carried E148Q. The majority of MEFV mutation carriers were Sephardic while non-carriers were mainly of Ashkenazi origin (72.7% vs. 45.7% and 47.4% vs. 9.1%, respectively, p = 0.02). SLE onset was significantly earlier in MEFV carriers (27.6 ± 9.7 vs. 38.2 ± 15.5 years, in carriers vs. non-carriers, p = 0.02). Hematologic and serologic parameters were comparable among mutation carriers and non-carriers. Febrile episodes were more common among MEFV mutation carriers (45.4% vs. 15.2%, p = 0.035) and there was a trend for excess episodes of pleuritis as well (54.5% vs. 23.7%, p = 0.06 in carriers vs. non-carriers, respectively). The frequency of secondary anti-phospholipid antibody syndrome was equivalent among the groups. Conversely, compound urinary abnormalities and renal failure was not observed among MEFV carriers yet was present in 33.4% and 18.6% of non-carriers ( p = 0.027 and 0.19, respectively). SLICC damage index and SLEDAI activity index did not differ significantly between the groups. MEFV mutation carriage appears to modify the SLE disease phenotype in that it contributes to an excess of inflammatory manifestations such as fever and pleuritis on the one hand, while thwarting more severe renal involvement on the other.

Expression of CD64 on polymorphonuclear neutrophils in patients with familial Mediterranean fever

Familial Mediterranean fever (FMF) is an autoinflammatory disease characterized by recurrent episodes of fever and serosal or synovial inflammation. We examined the utility of CD64 (FcγRI) expression in polymorphonuclear neutrophils (PMNs) as clinical and biological parameters in patients with FMF. We studied 12 Japanese FMF patients (mean age; 22·8 ± 15·5 years, male/female: 2/10), along with rheumatoid arthritis patients (RA, n = 38 male/female: 6/32, mean age; 52·2 ± 15·3 years), systemic lupus erythematosus (SLE, n = 15 male/female: 0/15, mean age; 38·5 ± 15·9 years) and 12 healthy subjects (male/female: 3/9, mean age; 37·9 ± 17·2 years). CD64 expression on PMNs was determined using flow cytometry. The quantitative expression of CD64 in patients with FMF (2439·6 ± 2215·8 molecules per PMN) was significantly higher than in healthy subjects (547·8 ± 229·5, P = 0·003) or in patients with RA (606·5 ± 228·2, P < 0·0001) and SLE (681·3 ± 281·1, P = 0·004). The increased CD64 expression on PMNs isolated from untreated FMF patients was down-regulated by colchicine treatment. NACHT-LRR-PYD-containing protein 3 (NLRP3) activation using MurNAc-L-Ala-D-isoGln (MDP) resulted in increased CD64 expression on PMNs from healthy subjects. Our results suggest that quantitative measurement of CD64 expression on PMNs can be a valuable tool to discriminate between FMF and autoimmune diseases.

Genotype-phenotype studies in a large cohort of Armenian patients with familial Mediterranean fever suggest clinical disease with heterozygous MEFV mutations

Familial Mediterranean fever (FMF) is an autoinflammatory disorder generally caused by recessively inherited mutations in the MEFV gene. FMF is quite prevalent in Armenian population in which majority of patients have two mutated alleles, yet in 18% of symptomatic patients just one mutation has been detected. To explain this finding, we analyzed the symptoms and genotypes of 1,299 patients, including 236 affected heterozygous patients with definite diagnosis of FMF. We selected a subset of 63 heterozygous, homozygous and asymptomatic normal individuals and completely sequenced their MEFV genes (exons) to discover any other mutations potentially missed by currently used screening method. Besides four synonymous polymorphisms in exon two and five, we found a T267I mutation in one heterozygous patient with a severe case of FMF who should have been designated as compound heterozygous, yet the other genotypes were all accurate. We used binomial probability distribution of symptoms in homozygous FMF patients to estimate the likelihood of their occurrences in heterozygous patients and demonstrated the assemblage of patients into groups with similar clinical criteria using statistical clustering. We found extremely high probabilities for the presence of FMF symptoms in heterozygous individuals and determined that symptoms were equally likely to occur in both analyzed genotypes. Therefore, our study supports the rising evidence that a single MEFV mutation could be associated with mild FMF symptoms. However, heterozygous patients presenting with severe phenotype should be further analyzed for less common second MEFV mutation using gene sequencing.

Involvement of the modifier gene of a human Mendelian disorder in a negative selection process

Background

Identification of modifier genes and characterization of their effects represent major challenges in human genetics. SAA1 is one of the few modifiers identified in humans: this gene influences the risk of renal amyloidosis (RA) in patients with familial Mediterranean fever (FMF), a Mendelian autoinflammatory disorder associated with mutations in MEFV. Indeed, the SAA1 α homozygous genotype and the p.Met694Val homozygous genotype at the MEFV locus are two main risk factors for RA.

Methodology/Principal Findings

Here, we investigated Armenian FMF patients and controls from two neighboring countries: Armenia, where RA is frequent (24%), and Karabakh, where RA is rare (2.5%). Sequencing of MEFV revealed similar frequencies of p.Met694Val homozygotes in the two groups of patients. However, a major deficit of SAA1 α homozygotes was found among Karabakhian patients (4%) as compared to Armenian patients (24%) (p = 5.10⁻⁵). Most importantly, we observed deviations from Hardy-Weinberg equilibrium (HWE) in the two groups of patients, and unexpectedly, in opposite directions, whereas, in the two control populations, genotype distributions at this locus were similar and complied with (HWE).

Conclusions/Significance

The excess of SAA1α homozygotes among Armenian patients could be explained by the recruitment of patients with severe phenotypes. In contrast, a population-based study revealed that the deficit of α/α among Karabakhian patients would result from a negative selection against carriers of this genotype. This study, which provides new insights into the role of SAA1 in the pathophysiology of FMF, represents the first example of deviations from HWE and selection involving the modifier gene of a Mendelian disorder.

Familial Mediterranean fever with a single MEFV mutation: where is the second hit?

OBJECTIVE

Familial Mediterranean fever (FMF) has traditionally been considered an autosomal-recessive disease; however, it has been observed that a substantial number of patients with clinical FMF possess only 1 demonstrable MEFV mutation. The purpose of this study was to perform an extensive search for a second MEFV mutation in 46 patients diagnosed clinically as having FMF and carrying only 1 high-penetrance FMF mutation.

METHODS

MEFV and other candidate genes were sequenced by standard capillary electrophoresis. In 10 patients, the entire 15-kb MEFV genomic region was resequenced using hybridization-based chip technology. MEFV gene expression levels were determined by quantitative reverse transcription-polymerase chain reaction. Pyrin protein levels were examined by Western blotting.

RESULTS

A second MEFV mutation was not identified in any of the patients who were screened. Haplotype analysis did not identify a common haplotype that might be associated with the transmission of a second FMF allele. Western blots did not demonstrate a significant difference in pyrin levels between patients with a single mutation and those with a double mutation; however, FMF patients of both types showed higher protein expression as compared with controls and with non-FMF patients with active inflammation. Screening of genes encoding pyrin-interacting proteins identified rare mutations in a small number of patients, suggesting the possibility of digenic inheritance.

CONCLUSION

Our data underscore the existence of a significant subset of FMF patients who are carriers of only 1 MEFV mutation and demonstrate that complete MEFV sequencing is not likely to yield a second mutation. Screening for the set of the most common mutations and detection of a single mutation appears to be sufficient in the presence of clinical symptoms for the diagnosis of FMF and the initiation of a trial of colchicine.

Gastric changes following colchicine therapy in patients with FMF

BACKGROUND

Familial Mediterranean fever (FMF) is also called recurrent polyserositis. The salient features of this disease include brief recurrent episodes of peritonitis, pleuritis, and arthritis, which are usually associated with fever. Colchicine is highly effective in the treatment of FMF and in preventing the development of recurrent attacks and amyloidosis, and it is essential to make the correct diagnosis and institute daily therapy with colchicine (0.5-0.6 mg bid). Colchicine is used to treat a variety of conditions but it is known to have gastrointestinal (GI) side effects. In this study, effects of colchicines on the gastrointestinal tract were evaluated in patients with FMF treated with colchicine.

METHODS

Biopsies were reviewed from 43 patients attending Ain Shams University Hospital (Egypt) who were diagnosed with FMF and treated with colchicine. One-hundred and twelve GI biopsies, obtained over a 14-year period, were reviewed. This included biopsies from stomach body (38), stomach antrum (50), and colon (24). In addition, gastric biopsies were reviewed from 17 control patients who did not have FMF and were not on colchicine.

RESULTS

Three patients known to have FMF and on colchicine therapy showed typical histological features of colchicine (metaphase mitoses, epithelial pseudoproliferation, mucin depletion, and frequent apoptosis). These features were seen only in gastric antral biopsies and not in colonic biopsies. None of the control group showed the characteristic morphological features of colchicine toxicity.

CONCLUSION

This is the first report of histological changes seen in the stomach following colchicine therapy. In contrast with previous reports, we did not find any definitive change in the large intestine. Our data show that gastric changes can be encountered in symptomatic patients who have recently had colchicine. If these finding are seen histologically, they merit correlation with the clinical impression and should not be interpreted as toxicity in isolation.

The familial Mediterranean fever protein, pyrin, is cleaved by caspase-1 and activates NF-kappaB through its N-terminal fragment

Familial Mediterranean fever (FMF) is an autoinflammatory disease caused by mutations in MEFV, which encodes a 781-amino acid protein denoted pyrin. We have previously shown that pyrin regulates caspase-1 activation and IL-1beta production through interaction of its N-terminal PYD motif with the ASC adapter protein, and also modulates IL-1beta production by interaction of its C-terminal B30.2 domain with the catalytic domains of caspase-1. We now asked whether pyrin might itself be a caspase-1 substrate, and found that pyrin is cleaved by caspase-1 at Asp330, a site remote from the B30.2 domain. Pyrin variants harboring FMF-associated B30.2 mutations were cleaved more efficiently than wild-type pyrin. The N-terminal cleaved fragment interacted with the p65 subunit of NF-kappaB and with IkappaB-alpha through its 15-aa bZIP basic domain and adjacent sequences, respectively, and translocated to the nucleus. The interaction of the N-terminal fragment with p65 enhanced entrance of p65 into the nucleus. The interaction of N-terminal pyrin with IkappaB-alpha induced calpain-mediated degradation of IkappaB-alpha, thus potentiating NF-kappaB activation. Absolute and relative quantities of cleaved pyrin and IkappaB-alpha degradation products were substantially increased in leukocytes from FMF patients compared with healthy controls. Our data support a new pyrin/caspase-1 pathway for NF-kappaB activation.

Mutations in NALP12 cause hereditary periodic fever syndromes

NALP proteins, also known as NLRPs, belong to the CATERPILLER protein family involved, like Toll-like receptors, in the recognition of microbial molecules and the subsequent activation of inflammatory and immune responses. Current advances in the function of NALPs support the recently proposed model of a disease continuum bridging autoimmune and autoinflammatory disorders. Among these diseases, hereditary periodic fevers (HPFs) are Mendelian disorders associated with sequence variations in very few genes; these variations are mostly missense mutations whose deleterious effect, which is particularly difficult to assess, is often questionable. The growing number of identified sporadic cases of periodic fever syndrome, together with the lack of discriminatory clinical criteria, has greatly hampered the identification of new disease-causing genes, a step that is, however, essential for appropriate management of these disorders. Using a candidate gene approach, we identified nonambiguous mutations in NALP12 (i.e., nonsense and splice site) in two families with periodic fever syndromes. As shown by means of functional studies, these two NALP12 mutations have a deleterious effect on NF-kappaB signaling. Overall, these data identify a group of HPFs defined by molecular defects in NALP12, opening up new ways to manage these disorders. The identification of these first NALP12 mutations in patients with autoinflammatory disorder also clearly demonstrates the crucial role of NALP12 in inflammatory signaling pathways, thereby assigning a precise function to this particular member of an emerging family of proteins whose putative biological properties are currently inferred essentially through in vitro means.

A very frequent mutation and remarkable association of R761H with M694V mutations in Turkish familial Mediterranean fever patients

Familial Mediterranean fever (FMF) is an autosomal-recessive disease. It is characterized by recurring fever, abdominal pain, and serositis. The Mediterranean fever (MEFV) gene is localized on 16p13.3 and more than 35 mutations have been described to date. There are some differences in the gene mutations of FMF in the various ethnic groups. The aim of this study is to determine the frequency of the mutations which has been reported comparatively rare, to define the most effective mutation set, and to select the most suitable DNA analysis system for Turkish FMF patients. Mutations in 330 Turkish FMF patients with typical phenotypes from various regions of Turkey were evaluated for the research purposes. These patients were analyzed for six MEFV gene mutations by the NanoChip Molecular Genetics Workstation. The most frequent mutation was M694V, identified in 50.00% of the alleles examined; M680I followed with 14.10% and V726A--9.70%. Consequently, we determined that R761H (n = 23; 3.48%) was the most frequent rare mutations in Turkish FMF patients. Frequency of the rare mutations were R761H (3.48%), E148Q (1.36%), and M694I (1.21%). All of these mutations were in the compound heterozygote state. Our study showed that R761H mutations were higher than it has been reported in literature until now and were mainly associated with M694V. We suggest that mutation R761H should be included in the mutation scanning analysis researches or considered if the patient has M694V/? mutation especially in Turkish FMF patients. Larger serial studies need to be done to investigate the rate and coexistence of these mutations.

Population genetics of familial Mediterranean fever: a review

In this review, some principal population genetic features of familial Mediterranean fever (FMF) are considered. These relate to the time and the place of founder mutations' origins, the role of ancient migrations and contacts between populations in the spatial spreading of the disorder, the influence of environmental factors and cultural traditions on the rate of FMF incidence, and possible selective advantage in carriers of FMF causing gene (MEFV) mutations.

PYPAF1 nonsense mutation in a patient with an unusual autoinflammatory syndrome: role of PYPAF1 in inflammation

OBJECTIVE

To gain insight into the pathophysiology of an unusual autoinflammatory syndrome, in a patient of Armenian origin, that mimicked familial Mediterranean fever (FMF) but with episodes triggered by generalized exposure to cold, and to further elucidate the controversial function of the protein encoded by PYPAF1, whose mutations (exclusively missense to date) have been identified in 3 hereditary recurrent fever syndromes.

METHODS

The patient's DNA was screened for mutations in both MEFV, the gene responsible for FMF, and PYPAF1. The ability of different recombinant PYPAF1 isoforms, expressed in HEK 293 cells, to regulate NF-kappaB signaling was subsequently assessed.

RESULTS

No disease-causing mutation was found in MEFV. However, a nonsense mutation (p.Arg554X) was identified in PYPAF1; this defect resulted in a truncated protein lacking all leucine-rich repeats. Study of the wild-type and mutant PYPAF1 recombinant proteins revealed that PYPAF1 inhibited NF-kappaB proinflammatory pathways, and that the identified nonsense mutation impaired this property.

CONCLUSION

These molecular and clinical findings, together with the clinical manifestations in the patient, which call into question the current nosology of the hereditary recurrent fever syndromes, are consistent with the hypothesis that PYPAF1 acts as an inhibitor of NF-kappaB signaling. They also provide a clear elucidation of the functional consequences of this nonsense PYPAF1 mutation not previously described in the literature, which result in a partial loss of function and may thereby explain the pathophysiology of the autoinflammatory syndrome observed in this patient.

Prevalence and distribution of MEFV mutations among Arabs from the Maghreb patients suffering from familial Mediterranean fever

Familial Mediterranean fever (FMF) is an autosomal recessive inherited disease caused by mutations in MEFV. This disease is characterized by recurrent episodes of fever accompanied with topical signs of inflammation. Some patients can develop renal amyloidosis. We prospectively investigated MEFV mutations in a cohort of 209 unrelated Arab patients from Maghreb (85 Algerians, 87 Moroccans, and 37 Tunisians) with a clinical suspicion of FMF. FMF is the main cause of periodic fever syndrome in Maghreb. The most frequent MEFV mutations in this cohort were M694V and M694I. These mutations account for different proportions of the MEFV mutations in Algeria (5%, 80%), Morocco (49%, 37%), and Tunisia (50%, 25%) patients. M694I mutation is specific to the Arab population from Maghreb. Other rare mutations were observed: M680L, M680I, A744S, V726A, and E148Q. We estimated the frequency of MEFV mutation carriers among the Arab Maghrebian population at around 1%, which is significantly lower than in non-Ashkenazi Jews, Armenians or Turks.

Intrafamilial segregation analysis of the p.E148Q MEFV allele in familial Mediterranean fever

BACKGROUND

Familial Mediterranean fever (FMF) is the most frequent of the recurrent inherited fevers. This autosomal recessive disorder is characterised by periodic episodes of fever and serositis that commonly affect the people of Arab, Armenian, Sephardic Jewish and Turkish origin. Most of the described MEFV gene anomalies responsible for the disease are missense mutations. In the absence of any functional test, epidemiological studies or pedigree analyses are the only means of proving the deleterious character of these sequence variations. Evidence was provided by our recent study using a population-based approach, that the p.E148Q allele is probably a benign polymorphism and not a disease-causing mutation. Its implication in FMF remains, however, controversial.

OBJECTIVE

To evaluate the segregation of the p.E148Q MEFV allele with FMF disease by using pedigree analysis.

PARTICIPANTS

21 patients and 48 unaffected relatives belonging to 18 independent families with FMF.

RESULTS

Segregation analysis of the p.E148Q allele was compatible with a Mendelian autosomal recessive transmission of the disease phenotype in only three families. In 15 of 18 families, segregation was partly or completely defective. The p.E148Q allele was not transmitted to 14 of 19 (74%) affected children.

CONCLUSIONS

No evidence of preferential transmission of p.E148Q from heterozygous parents to their affected offspring was observed. MEFV is not associated with the clinical manifestations of several patients carrying this variant. Considering p.E148Q to be a benign polymorphism should reduce the possibility of false-positive diagnoses, while highlighting genetic heterogeneity in FMF.

MEFV analysis is of particularly weak diagnostic value for recurrent fevers in Western European Caucasian patients

OBJECTIVE

Familial Mediterranean fever (FMF) is an autosomal-recessive disorder characterized by recurrent attacks of fever, with abdominal, thoracic, or articular pain. FMF is particularly common in Mediterranean populations, while other populations are rarely affected. MEFV gene analysis provides the only objective diagnostic criterion for FMF. However, the spectrum of MEFV mutations, which was first established in classically affected populations, remains insufficiently studied in other populations. The purpose of this study was to assess involvement of MEFV in the phenotype of western European Caucasian patients with a clinical diagnosis of FMF.

METHODS

Mutation analysis was performed in 208 Caucasian patients from western Europe, by screening for the most common MEFV mutations in exons 2, 3, 5, and 10, and by sequencing the promoter region and the whole MEFV coding sequence in 21 of these patients.

RESULTS

None of the patients carried 2 mutated alleles. Only 2 patients carried 1 mutated allele.

CONCLUSION

FMF-like syndromes in western European Caucasian populations cannot be explained by MEFV mutations. These results should be helpful in avoiding laborious and costly MEFV molecular analyses that, at the population level, seem to be of poor diagnostic value in the case of western European Caucasian patients, and rather should prompt a search for other causes in those patients.

Familial Mediterranean fever (FMF) in Lebanon and Jordan: a population genetics study and report of three novel mutations

Familial Mediterranean fever (FMF) is an autosomal recessive disease mostly frequent in Mediterranean populations. Over 50 mutations have been identified in the gene responsible for the disease, MEFV. The present study reports the frequencies of MEFV mutations in 558 Lebanese and 55 Jordanian FMF patients and points out the severity of the M694V frequently observed mutation among these patients. Three novel mutations, T177I, S108R and E474K were also identified in the Lebanese group. An excess of homozygotes and a deficit of heterozygotes were observed in both samples when compared to the expected number of observed genotypes under the Hardy-Weinberg hypothesis. Homozygotes for M694V and M694I were still in excess in the Lebanese group of patients, even after consanguinous homozygotes were removed, or population structure was considered. This excess is therefore neither due to consanguinity nor to subgroups in the Lebanese population, but rather to more remote consanguinity or to a selection bias favoring the census of these genotypes. The fact that FMF female patients were less censed than male patients may be due to the greater resistance of females to pain and to the possibility of confusing abdominal and gynecological pain. The phenotypic heterogeneity of the FMF could then originate both from genetic causes like allelic heterogeneity or modulating genes, and cultural background facing the physiological consequences of genotypes at risk.

[Familial Mediterranean fever among the autoimmune diseases]

During the first attacks of familial Mediterranean fever, each of the disease symptoms can suggest a series of disorders. When the disease is older, the recurrence of symptoms may simulate some systemic diseases, but mainly suggests familial Mediterranean fever, one of a group of hereditary autoinflammatory diseases. Before the gene for familial Mediterranean fever was identified, various sets of criteria were used for diagnosis. The presence of MEFV mutations confirms the diagnosis, but the clinical criteria still determine who should undergo this genetic testing. The genotype-phenotype correlations add a prognostic dimension to the mutations identified. Genotyping can also lead to the diagnosis of the other autoinflammatory diseases, which constitute the basis of the differential diagnosis of familial Mediterranean fever. The hyperimmunoglobulinemia D syndrome (HIDS) is very similar to familial Mediterranean fever in its recessive transmission and abdominal and articular symptoms. It can be distinguished by the European origin of the patients, the presence of cervical lymph nodes and the increased IgD levels. Of the diseases with dominant transmission, the TNF receptor-associated periodic syndromes (TRAPS) are suggested by periorbital edema and migrating inflammatory cellulitis. Muckle and Wells syndrome is revealed by episodes of fever with urticaria and arthralgia, complicated by deafness and amyloidosis. Mutations in the same gene are responsible for two disorders, both appearing in childhood: familial cold urticaria syndrome (FCUS) and chronic infantile neurocutaneous articular syndrome (CINC). The pathogenesis of familial Mediterranean fever is still unclear. Pyrin/marenostrin, the protein produced by the MEFV gene, appears to hae a physiological antiinflammatory effect that inhibits proinflammatory cytokines. Mutation of the gene may eliminate this feedback mechanism and expose the patient to flares from any inflammatory stimulus, even minimal. Amyloid is produced by the serum amyloid A protein (SAA), and its occurrence is influenced by the type of MEFV mutation, but also the genotype of the gene producing SAA.

Maladie périodique, symptomatologie clinique et biologique

Familial Mediterranean fever is the best known of the recurrent hereditary autoinflammatory diseases. It predominantly affects subjects of Mediterranean origin, Sephardic Jews in particular. Its gene, MEFV, is located on chromosome 16 and has autosomal recessive transmission, with incomplete penetration. It codes for a protein called pyrin or marenostrin, which is probably involved in the inflammatory process. In most cases, the first episodes appear before the age of 20 years and very rarely after the age of 40. Episodes usually last a few days, although they may extent over several weeks when localized in joints. Fever, occasionally pseudo-malaria, may accompany various symptoms, the most frequent of which are abdominal, articular, pleural or cutaneous. The abdomen is the classic site of this disease, and acute abdominal flares masquerade as abdominal emergencies. Musculoskeletal involvement is revealed by episodes of inflammation of the joints (more often mono- than oligoarthritis) and muscle pain. The flares are usually brief and totally reversible. Flares of thoracic pain corresponding to pleural inflammation and erysipelas-like skin eruptions have been observed. Acute symptoms disappear between flares, but hepatic splenomegaly, swollen lymph nodes or abnormal fundus of the eye may persist. Laboratory findings are typical of nonspecific inflammation, accompanied by moderate hyperleukocytosis during the flares.

Musculoskeletal disorders in secondary amyloidosis and hereditary fevers

Amyloidosis remains a severe potential complication of many chronic inflammatory disorders, foremost of rheumatoid arthritis. It is not exactly known why some patients develop a progressive amyloidosis while others do not, although latent deposits may be present. It is likely that more potent anti-inflammatory drugs recently used in rheumatoid arthritis have led to a decrease of amyloid-associated (AA) amyloidosis. However, overt amyloidosis remains a severe complication of some chronic inflammatory disorders and it has a poor prognosis. Hereditary fevers are a group of diseases characterized by intermittent bouts of clinical inflammation with focal organ involvement, mainly abdomen, musculoskeletal system and skin. The most frequent is familial Mediterranean fever which affects patients of Mediterranean descent all over the world. Three other types have been recently characterized clinically as well as genetically. A thorough diagnosis is warranted, as clinical and therapeutic management is specific for each of these diseases.