<Emphasis Type="Italic">MEFV</Emphasis> mutations in patients with familial Mediterranean fever from the Aegean region of Turkey

Familial Mediterranean Fever (FMF) which is frequently present in Mediterranean populations is caused by mutations in the MEFV gene. According to recent data, MEFV mutations are not the only cause of FMF, but these are major genetic determinants which cause FMF. It has also been suggested that there may be a number of other genes causing FMF. The MEFV gene is located at 16p13.3 and encodes a protein, pyrin/marenostrin. More than 70 disease associated mutations and totally 186 mutations and polymorphisms have been defined in affected individuals. We have retrospectively evaluated the molecular test results of 1,201 patients identified as having FMF clinical symptoms referred to the Molecular Genetics Laboratory of the Department of Medical Genetics, Faculty of Medicine, Ege University, Izmir/Turkey over the last 4 years. Patients were tested for 12 common mutations in the MEFV gene using a strip assay method (Innogenetics, Belgium). Out of the 1,201 patients tested (2,402 chromosomes) in the Aegean region in Turkey, 654 (54.45%) did not carry any mutations, among the 547 (45.55%) patients with mutations 246 patients were either homozygous (101) or compound heterozygous (145), 296 carried only one detected mutation, and five patients had three mutations. Allelic frequencies for the four most common mutations in the mutation positive groups were 47.60% (M694V), 16.75% (E148Q), 12.95% (V726A), 11.94% (M680I G/C).The remaining alleles (10.76%) showed rare mutations which were R761H, P369S, A744S, K695R, F479L, M694I. When the frequencies of mutations detected in our group were compared to the frequencies reported in the other regions of Turkey, an increase in V726A mutation frequency was observed. No patient showed a I692del mutation which is sometimes evident in other Mediterranean populations.     

Familial Mediterranean fever in Syrian patients: <Emphasis Type="Italic">MEFV</Emphasis> gene mutations and genotype–phenotype correlation

Familial Mediterranean fever is an autosomal recessive disorder characterized by recurrent attacks of abdominal pain, synovitis and pleuritis. MEFV gene mutations are responsible for the disease. The objective of this study was to identify the frequency and distribution of 12 MEFV mutations in 153 Syrian patients and perform a genotype–phenotype correlation in the patients’ cohort. Of the 153 unrelated patients investigated, 97 (63.4%) had at least one mutation. The most frequent mutation was M694V (36.5%), followed by V726A (15.2%), E148Q (14.5%), M680I (G/C) (13.2%), and M694I (10.2%) mutations. Rare mutations (R761H, A744S, M680I (G/A), K695R, P369S, F479L and I692del) were also detected in the patients. M694V was associated with the severe form of the disease. The identification of a significant number of FMF patients with no mutations or only one known mutation identified indicates the presence of new mutations in the MEFV gene which will be investigated in the future.     

The spectrum of FMF mutations and genotypes in the referrals to molecular genetic laboratory at Kırıkkale University in Turkey

Familial Mediterranean Fever (FMF) is an autosomal recessive genetic disorder characterised by recurrent and self-limited abdominal pain, synovitis and pleuritis. MEFV gene mutations are responsible from the disease and its protein product, pyrin or marenostrin, plays an essential role in the regulation of the inflammatory reactions. MEFV gene contains 10 exons and most of the mutations have been found on the last exon. Up to date, 152 mutations and polymorpisms have been reported inwhere V726A, M694V, M694I, M680I and E148Q are the most common mutations. In this study, MEFV allele frequencies of 136 individuals (60 from Pediatry, 76 from Internal Medicine) have been evaluated, and compared with each other. Asymptomatic individuals with FMF family history (4 from Pediatry, 6 from Internal Medicine) were excluded from the analysis. The prominent mutations indicated in the Pediatry group are V726A, M694V and M680I (G/C) and with the allele frequency of 0.06, 0.05 and 0.04 respectively while they were E148Q, M694V, M680I (G/C) in the Internal Medicine group with the allele frequency of 0.12, 0.08 and 0.04. The E148Q mutation is significantly overrepresented in the adult referrals (P = 0.02). Mutation on both alleles was observed in only 12% of cases. Overall mutation frequency was low, seen in 26.2% (66/252). However, when only diagnosed patients were analyzed it is 72.7% (16/22). It is also interesting that 63% of individuals are female that there may be sex influence on FMF phenotype.     

Prevalence of common <Emphasis Type="Italic">MEFV</Emphasis> mutations and carrier frequencies in a large cohort of Iranian populations

Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disorder caused by mutations in the MEFV gene. The disease is especially common among Armenian, Turkish, Jewish and Middle East Arab populations. To identify the frequency and the spectrum of common MEFV mutations in different Iranian populations, we investigated a cohort of 208 unselected asymptomatic individuals and 743 FMF patients. Nine hundred and fifty-one samples were analysed for the presence of 12 MEFV mutations by PCR and reverse-hybridization (FMF StripAssay, ViennaLab, Vienna, Austria). Confirmatory dideoxy sequencing of all MEFV gene exons was performed for 39 patients. Fifty-seven (27.4%) healthy individual carried mutant MEFV alleles. Three hundred and ninety-one (52.6%) FMF patients were found positive for either one (172/743; 23.1%), two or three MEFV mutations. Using dideoxy sequencing, three novel variants, A66P, R202W and H300Q, could be identified. Our analysis revealed an allele frequency and carrier rate of 15.6 and 27.4%, respectively, among healthy Iranians. Still moderate compared to neighbouring Armenia, but higher than in Turkey or Iraq, these data suggest that FMF is remarkably common among Iranian populations. E148Q was most frequent in the group of healthy individuals, whereas M694V was the most common mutation among FMF patients, thereby corroborating previous studies on MEFV mutational spectra in the Middle East. Accordingly, MEFV mutations are frequent in healthy Iranian individuals across different ethnic groups. Based on this finding, the awareness for FMF and the implementation of augmented carrier screening programmes considering the multiethnic nature of the Iranian population should be promoted.     

Mediterranean fever gene mutations: correlation with cytotoxic T‐lymphocyte‐associated antigen 4 gene polymorphism

Mutations in the Mediterranean fever (MEFV) gene lead to familial Mediterranean fever (FMF), a pro‐inflammatory state characterized by outbursts of inflammatory cytokines. The aims of this study were to identify the common mutations of MEFV gene in Egyptian patients with FMF, to study cytotoxic T lymphocyte associated antigen 4 (CTLA‐4) gene polymorphism and to evaluate correlations between CTLA4–1661 polymorphisms and MEFV mutations and clinical symptoms. Four hundred and twenty‐four patients with clinical pictures suspicious of FMF were enrolled in this study. Mutations in MEFV gene were confirmed by reversed hybridization. Patients with homozygous and compound heterozygous mutations and 120 healthy controls were investigated for polymorphism of ?1661 CTLA4 gene and the findings correlated with disease incidence and clinical symptoms of the disease. Ninety‐seven patients had single heterozygous mutations and 78 had compound heterozygous or homozygous MEFV gene mutations. M694I/V726A was the most common genotype (14.1%), followed by homozygous M694I. There was no statistically significant difference between patients and controls in incidence of ?1661 A/G single nucleotide polymorphism CTLA4 (P = 0.189), nor any significant correlation with any of the clinical symptoms of FMF and MEFV gene mutations.

     

Common MEFV gene mutations in Turkish patients with Behcet's disease

Behcet's disease (BD) is a chronic systemic inflammatory disorder whose etiology has not been fully established yet. The MEditerranean FeVer (MEFV) gene has been identified as the cause of Familial Mediterranean Fever (FMF). BD shows similarities with FMF, in terms of clinical findings and treatments, as well as their geographical and ethnic co-occurrence. In this study we investigated common MEFV gene mutation frequencies in Turkish patients with BD in an area of Turkey where both diseases are frequently encountered. We screened 207 BD patients who had no symptoms and family history for FMF and 200 healthy subjects for five common MEFV gene mutations (E148Q, M680I, M694V, V726A, P369S) and clinical features. Seventy-five patients were found to carry a single MEFV mutation, and six patients were compound heterozygous. The difference in the frequency of the MEFV mutation between the BD and control groups was statistically significant (p < 0.001, odds ratio [OR] 2.74, 95% confidence interval [CI] 1.75–4.29). The frequencies of E148Q and M680I mutations were significantly higher in the BD group (p = 0.001, p = 0.046, respectively). The frequency of uveitis was significantly lower in patients with the mutation than in patients without the mutation (p = 0.029, OR 0.54, 95% CI 0.30–0.98). There was no statistical significance between carriers and non-carriers with respect to gender and other manifestations of BD. The frequency of the MEFV mutation was significantly higher in patients with BD compared to the healthy control group. Based on our results, MEFV mutations appear to have a role in the pathogenesis of BD.     

Evaluating <Emphasis Type="Italic">MEFV</Emphasis> mutation frequency in Turkish familial Mediterranean fever suspected patients and gender correlation: a retrospective study

Familial Mediterranean fever (FMF) is the most frequent hereditary inflammatory disease. FMF causes different clinical manifestations in different ethnic groups and countries. In this study, we retrospectively reviewed the records of 1,152 FMF suspected patients (673 female and 479 male) from November 2006 to December 2010. A commercial kit assay for the identification of MEFV (Mediterranean fever) gene mutations based on PCR and reverse-hybridization was used to investigate 12 mutations of the MEFV gene. 52.17% of 1,152 FMF suspected patients had MEFV mutation and 45.25% of them were male. The rate of MEFV mutation among male and female patients were 56.78 and 48.88%, respectively. These results were statistically significant and might support the suggestion that FMF had much more penetrance in male patients (P = 0.009). Not any significant difference was observed between the male and female patients in terms of heterozygote and homozygote mutation carriage rate (P = 0.071). Also not any significant difference was observed between the male and female patients in terms of compound heterozygote mutation carriage rate (P = 0.058).     

The frequency of Familial Mediterranean fever gene mutations and genotypes at Kirikkale and comparison with the mean of regional MEFV mutation frequency of Turkey

In this study we have retrospectively analysed the mutation spectrum of the 351 Familial Mediterranean fever patients referred to K?r?kkale University Faculty of Medicine, Department of Medical Genetics Laboratory over a period of 5 years and compared them with Turkey’s mean. We have found 11 different mutations, including rare mutations such as F479L, K695R, M680I(G/A) and 45 different genotypes showing the heterogeneity of MEFV mutations in Central Anatolia. The most three prevalent mutations were M694V (14.8 %), E148Q (7.1 %) and M680I(G/C) (4.1 %) in accordance with the literature. We have also investigated R202Q in our routine molecular diagnosis. Mutation causing R202Q (c.605G > A) change was described as a frequent polymorphism and G allele was found in linkage disequilibrium (LD) with M694V. There are limited number of studies investigating R202Q, some of them implicate that its homozygote state is disease causing. We showed the high frequency of R202Q (23.7 %) with and without M694V in all the groups analysed and its high LD rate with M694V in the diagnosed group. Our study is reflecting the mutational heterogeneity of MEFV and summarize mutational spectrum of Turkey’s geographical regions and overall Turkey.     

Clinical and molecular analysis of common MEFV gene mutations in familial Mediterranean fever in Sivas population

Familial Mediterranean fever (FMF) is the most frequent hereditary inflammatory disease characterized by self-limited recurrent attacks of fever and serositis. The aim of the current study is to determine the frequency of the mutations in 365 suspected FMF patients and to reveal whether there is a correlation between genotype and phenotype of these patients. All patients were clinically examined according to Tell-Hashomer FMF criteria and were screened genetically in terms of common 12 Mediterranean fever gene (MEFV) mutations. Various point mutations were detected in 270 (74%) patients. The most frequent mutation was M694V (26.85% of the alleles) and was followed by E148Q (15.55%), M680I (G/C) (9.62%) and V726A (7.96%). Patients who bear M694V homozygous mutation had most severe disease phenotype and high risk for amyloidosis (P = 0.04). Our results indicate that Sivas population has a wide range of heterozygous mutated carriers of MEFV gene and there is a high frequency of E148Q allele when compared to the other Mediterranean groups.     

Homozygous M694V as a risk factor for amyloidosis in Turkish FMF patients

Secondary amyloidosis is the most severe complication of familial Mediterranean fever (FMF). Since the M694V mutation was associated with clinical severity, it was expected to be associated with amyloidosis as well. However, a number of contradicting reports have been published, especially pertinent to Turkish patients nearly 10 years ago. The aim of this study was to analyze recent data regarding the association between M694V mutation and amyloidosis among FMF patients in Turkey.We conducted a comprehensive review of the literature regarding the role of M694V mutation in the development of amyloidosis secondary to FMF. Twenty-seven papers from 20 centers including 3505 Turkish subjects were reviewed.Four-hundred patients had amyloidosis and homozygous M694V was detected in 189 (47%) of the 400 amyloidotic patients which was significantly higher than that in the FMF patients not developing amyloidosis (p < 0.0001).In the presented analysis we were able to reach a patient number of 400 which is much higher than all those published hitherto. Our findings confirmed that homozygous M694V is associated with amyloidosis in the Turkish population as well similar to Armenia, Israel, and Arabian countries. The necessity to treat asymptomatic or mildly symptomatic FMF patients with this genotype, even in countries where amyloidosis is rare, should be considered carefully.     

Genotype-phenotype correlation in Japanese patients with familial Mediterranean fever: differences in genotype and clinical features between Japanese and Mediterranean populations

Introduction

Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disease characterized by recurrent self-limiting fever and serositis that mainly affects Mediterranean populations. Many patients with FMF have been reported in Japan due to increasing recognition of this condition and the availability of genetic analysis for the gene responsible, MEFV. The present study was performed to elucidate the clinical characteristics of Japanese FMF patients and to examine the precise genotype-phenotype correlation in a large cohort of Japanese FMF patients.

Methods

We analyzed the MEFV genotypes and clinical manifestations in 116 patients clinically diagnosed as having FMF and with at least one mutation.

Results

The most frequent mutation in Japanese patients was E148Q (40.2%), followed by M694I (21.0%), L110P (18.8%), P369S (5.4%), and R408Q (5.4%). In contrast, common mutations seen in Mediterranean patients, such as M694V, V726A, and M680I, were not detected in this population. The clinical features with M694I were associated with more severe clinical course compared to those seen with E148Q. P369S/R408Q showed variable phenotypes with regard to both clinical manifestations and severity. Patients with M694I showed a very favorable response to colchicine therapy, while those with P369S and R408Q did not.

Conclusions

Clinical features and efficacy of treatment in Japanese FMF patients vary widely according to the specific MEFV gene mutation, and therefore genetic analysis should be performed for diagnosis in cases of Japanese FMF.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0439-7) contains supplementary material, which is available to authorized users.     

Comparison of amplification refractory mutation system and polymerase chain reaction-restriction fragment length polymorphism techniques used for the investigation of MEFV gene exon 10 point mutations in familial Mediterranean fever patients living in Cukurova region (Turkey)

Familial Mediterranean fever (FMF) is an autosomal recessive inherited disease characterized by recurrent fever, serositis and arthritis. The disease is highly prevalent in Mediterranean basin populations. Recently, the gene responsible for FMF (MEFV) was cloned and at least 40 MEFV gene mutations have been identified. The most frequently observed mutations in the MEFV gene are M694V, M694I, M680I, and V726A. These occur within exon 10 of the gene, and account for 85% of the known MEFV alleles. In this study, the reliability and economical aspects of amplification refractory mutation system (ARMS) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques were compared for analyzing the frequencies of the major point mutations of 90 unrelated patients with FMF from the Cukurova region in Turkey. Both techniques yielded similar results: The ratio of independent alleles of 90 patients carrying one of the tested mutations was 81.1%; patients consisted of 12 different genotypes. In 64 of 90 patients (71.1%) mutations were observed in both alleles. Thirty-six patients (40%) were homozygous for the same mutation, 28 (31.1%) were heterozygous for different mutations. Eighteen patients (20%) were heterozygous for one allele with one of the four mutations but the other allele was unknown. In 8 patients (8.8%) no mutation could be detected. The most frequently observed mutation was M694V (51.66%), followed by M680I (17.22%), V726A (10.55%), and M694I (1.66%). In conclusion ARMS and PCR-RFLP techniques were equally reliable to detect the mutations in Turkish FMF patients. However, the ARMS technique was found to be more rapid and economical than the PCR-RFLP techniques.     

Common Familial Mediterranean Fever gene mutations in a Turkish cohort

Familial Mediterranean Fever (FMF) is an autosomal recessive autoinflammatory disorder with the responsible gene of MEFV which primarily affects Jewish, Armenian, Turkish and Arab populations. The FMF gene (MEFV) has recently been cloned to chromosome 16p, which encodes pyrin. In the present study, we enrolled 2,067 unrelated patients with the suspicion of FMF in Middle Anatolia between the years 2006–2009 and identified the 12 MEFV mutations. DNA was amplified by PCR and subjected to reverse hybridization for the detection of MEFV gene mutations. Among the 2,067 patients, 866 (41.9%) were males and 1,201 (58.1%) were females. The mutations were homozygous in 176 (16.85%) patients, compound heterozygous in 314 (30.1%) patients, heterozygous in 546 (52.25%) patients and the other forms of mutations were found in 8 patients (0.76%). No mutation was detected in 1,023 (49.5%) patients. The most frequent mutations were M694V, M680I (G/C), E148Q and V726A. We could not find any significant differences between the two common mutations according to the gender. The high incidence of MEFV gene mutations in the Turkish population indicated that newborn screening may be discussed in the future. Because of the ethnic origin of Anatolia, larger serial analyses are necessary to investigate the rate and coexistence of these mutations.     

Next-generation screening of a panel of genes associated with periodic fever syndromes in patients with Familial Mediterranean Fever and their clinical characteristics

Familial Mediterranean Fever (FMF) is a hereditary fever syndrome that primarily affects Mediterranean populations. For the study, total number of 182 patients with FMF disease were enrolled and screening of a panel of genes , called “fever panel” which comprises 17 genes, was performed. The most common mutations in MEFV gene were homozygous M694V missense mutation (4.3%) and R202Q missense mutation (4.9%). The most common heterozygous mutations were R202Q (26.5%), M694V (25.9%) and E148Q (11.9%). Compound heterozygous and homozygous mutations were also detected. Also, different types of mutations were identified in NOD2, CARD14, NLRP12, NLRP3, NLRP7, IL1RN, LPIN2, TNFRSF1A, MVK and PSTPIP1 genes. Two novel missense variations in the MEFV gene, Gln34Pro and Ile247Val, which have not been previously reported in the databases, were identified. Also, Thr91Ile missense variation in the NOD2 gene, Gly461Cys missense variation in NLRP3 and Tyr732Stop nonsense variation in LPIN2 were firstly identified. The results of the current study suggest that in addition to the MEFV gene which has an important roles in FMF, molecular screening of other genes related to other autoinflammatory diseases might provide support in suspected cases and provide detailed information about the course of the disease.     

Phenotype-genotype updates from familial Mediterranean fever database registry of Mansoura University Children’ Hospital,Mansoura, Egypt

BACKGROUND:

Familial Mediterranean fever (FMF) is autosomal recessive disease that affects people from Mediterranean region, Europe and Japan. Its gene (Mediterranean fever [MEFV]) has more than 100 mostly non-sense mutations.

OBJECTIVES:

The objective of the following study is to provide some phenotype-genotype correlates in FMF by categorizing the Egyptian FMF cases from Delta governorates after analysis of the four most common mutations of MEFV gene (M680I, M694I, M694V, V726A).

SUBJECTS AND METHODS:

Clinically, suspected FMF cases using Tel-Hashomer criteria were enrolled in the study. Cases were referred to Mansoura University Children''s Hospital that serves most of the most middle Delta governorates, in the period from 2006 to 2011. Subjects included 282 males and 144 females, mean age of onset 9.3 ± 2.2 years. All cases were analyzed for these mutations using amplification refractory mutation system based on the polymerase chain reaction technique. Five FMF patients agreed to undergo renal biopsy to check for development of amyloidosis. Analysis of data was carried out using SPSS (SPSS, Inc., Chicago, IL, USA).

RESULTS:

Mutation was found in 521 out of 852 studies alleles, the most frequent is M694V (35.4%) followed by M694I, V726A and M680I. 11 cases were homozygous; 7 M694V, 3 M680I and only one M694I case. Severe abdominal pain occurred in 31 (7.28%) but severe arthritis in 103 cases (24.2%). Strong association was found between arthritis and homozygous mutant compared with single and double heterozygous (72.7% vs. 33.3% and 20.24%, P < 0.001). Four amyloid cases were M694V positive.

CONCLUSION:

M694V allele is the most common among Egyptian FMF especially those with amyloidosis. We recommend routine check for amyloidosis in FMF cases to statistically validate this link.     

Arthritis patterns in familial Mediterranean fever patients and association with M694V mutation

Familial Mediterranean fever (FMF) is an autosomal recessive disorder characterized by recurrent attacks of febrile peritonitis, pleuritis and synovitis. Arthritis is a common and important feature of FMF. The clinical spectrum of arthritis in 71 FMF patients was retrospectively investigated. Mutations in the familial Mediterranean (MEFV) gene were screened. Unlike the previous reports on arthritis of FMF, most of the FMF patients (59%) in this study had symmetric two-joint arthritis whereas monoarticular, oligoarticular and polyarticular arthritis was presented in 20, 8 and 10% of the patients, respectively. Knees were affected in 45 (63%) patients, ankles in 30 (42%), elbows in 11 (15%), wrists in 12 (17%), hips in 12 (17%), small joints of the hands 7 (10%), small joints of the feet 2 (3%) and sacroiliac in 1 (1%). Destruction of the hip was observed in 2 (3%) patients and required hip replacement. Amyloidosis developed in 2 (3%) of our patients. Mutations in the MEFV gene were identified in 50 (71%) patients and the most dominant mutation detected was M694V (64%). Since FMF can be diagnosed by a simple DNA mutation analysis, all arthritis patients of certain origins (Arabs, Turks, Armenians and Jews) should be tested for FMF in order to prevent the complications (amyloidosis and protracted arthritis) by introducing colchicine which is the treatment of choice for FMF.     

Screening of common and novel familial mediterranean fever mutations in south-east part of Turkey

Familial mediterranean fever (FMF) is an autosomal recessive autoinflammatory disorder (MIM# 249100), particularly common in populations of Mediterranean extraction. MEFV gene, responsible for FMF, encoding pyrin has recently been mapped to chromosome 16p13.3. In the present study, 3,341 unrelated patients with the suspicion of FMF in south-east part of Turkey between the years 2009 and 2013 were enrolled and genomic sequences of exon 2 and exon 10 of the MEFV gene were scanned for mutations by direct sequencing. We identified 43 different type of mutations and 9 of them were novel. DNA was amplified by PCR and subjected to direct sequencing for the detection of MEFV gene mutations. Among the 3,341 patients, 1,598 (47.8 %) were males and 1,743 (52.1 %) were females. The mutations were heterozygous in 806 (62.3 %), compound heterozygous in 188 (14.5 %), homozygous in 281 (21.8 %) and mutations had complex genotype in 17 (1.32 %) patients. No mutation was detected in 2,051 (61.4 %) patients. The most frequent mutations were M694V, E148Q, M680I(G/C) and V726A. We could not find any significant differences between the two common mutations according to the gender. Molecular diagnosis of MEFV is a useful tool in clinical practice, thus a future study relating to genotype/phenotype correlation of FMF in more and larger group in Turkish population involving the whole MEFV gene mutations is necessary.     

Investigation of C5a receptor gene 450 C/T polymorphism in Turkish patients with familial Mediterranean fever

Familial Mediterranean fever (FMF) is a genetic disorder with acute inflammatory serosal attacks due to MEFV gene mutations which resides in chromosome 16. Lack of a C5a inhibitor activity in the peritoneum has previously been proposed in part to contribute in propagation of the serosal inflammation in FMF attacks. The aim of this study is to investigate C5a receptor (C5aR) gene polymorphism in patients with FMF and its relation to the main features of the disease. A polymorphism in the coding region of C5aR gene leading to C to T transition at nucleotide position 450 has been investigated in 85 non-related Turkish FMF patients and 160 non-related healthy controls by using PCR-RFLP. The frequencies of C5aR gene 450 CT genotype and T allele were not significantly different between Turkish FMF patients and healthy subjects (14.12 and 8.24% for FMF vs. 10 and 5% for controls, respectively). C5aR gene 450 CT genotype tended to associate with the presence Henoch-Schonlein purpura (OR: 1.25, 95% CI: 0.917–1.704, P = 0.017) but with no other clinical findings of the disease. C5aR polymorphism might be searched in populations having high prevalence of FMF.     

The relative contribution of environmental and genetic factors to phenotypic variation in familial Mediterranean fever (FMF)

Introduction

Familial Mediterranean fever (FMF) is an autosomal recessive disease, caused by mutations in the FMF gene MEFV (MEditerranean FeVer). It has a large phenotypic diversity even in patients with similar genotypes. Despite evidence that environmental factors (EFs) and genetic factors, including MEFV mutations (such as M694V, E148Q) and background modifier genes (MGs), affect the clinical manifestations of FMF, the relative contribution of each remains unknown.

Methods

To investigate the relative contribution of environmental and genetic factors to the phenotype of FMF, we compared the intra-pair clinical concordance of 10 mono and 7 dizygotic twins with FMF. The part played by EFs was determined by the phenotypic discordance of the monozygous twins, and the MGs effect was determined by deducing the environmental effect, computed for MZ twins, from the phenotypic discordance of the dizygous twins.

Results

The mean ± SD of intra-pair concordance was higher in the MZ than in DZ twin group (88.1 ± 13.2 vs. 70.7 ± 14.1 respectively, P value < 0.05). Based on the concordance in clinical manifestations in MZ and DZ twins, the environmental effect on the phenotype of FMF is estimated as 11.9% ± 6.6% and the MGs effect as 17.4% ± 15.5% in average.

Conclusions

In FMF the phenotype is affected by MEFV mutations, MGs and EFs in an estimated ratio of about 6:1.5:1 respectively.     

Genetic analysis of C5a receptors in neutrophils from patients with familial Mediterranean fever

Familial Mediterranean fever (FMF) is an autoinflammatory disease, characterized by MEFV gene mutations and self-limited recurrent episodes of fever and localized serositis. Complement system is a key regulator of the inflammatory process. The aim of this study was to investigate the genetic alterations and mRNA expression pattern of C5aR and C5L2 genes in neutrophils from attack-free FMF patients. No mutations were observed in the two receptors’ genes, while the genetic alteration observed in the C5aR1 gene was identified as N279 K polymorphic variant. Furthermore, lower mRNA expression of C5L2 gene was observed in neutrophils from FMF patients compared to control subjects. The binding capacity of rhC5a and the ability to produce reactive oxygen species was similar in neutrophils from healthy subjects and FMF patients and independent of the presence of N279 K polymorphism or mRNA expression of C5L2.