Prevalence of known mutations in the MEFV gene in a population screening with high rate of carriers

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

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

Presentation of a new mutation in FMF and evaluating the frequency of distribution of the MEFV gene mutation in our region with clinical findings

Familial Mediterranean Fever (FMF), which is an autosomal recessive disease characterized by recurrent self-limiting fever, peritonitis, pleuritis, arthritis and erysipelas-like erythemas, has been common among ethnic groups such as Turkish, Armenian, Arabic and Jewish. The clinical presentation is caused by mutations in the MEFV gene encoding the Pyrin protein. In this study, we aimed to present a new mutation that has not been previously defined from the mutations in the MEFV gene which is responsible for the genetic pathology of familial Mediterranean fever and to evaluate the frequency of distribution of the MEFV gene mutation among different ethnic groups living in our region. In present retrospective study, a total of 2639 clinically suspected FMF patients who were referred to Hatay Mustafa Kemal University Hospital between 2010 and 2017 were recorded. MEFV gene mutations were observed using DNA sequence analysis. MEFV mutations were found in 2079 of the 2639 patients (78.7%) Among these patients 184 (6.97%) were homozygous, while 1365 (51.72%) were heterozygous. The most frequently observed mutation was R202Q (1319, 19.55%) followed by E148Q (n = 476, 7.05%), M694V (n = 439, 6.51%), V726A (n = 146, 2.16%) and M680I (n = 135, 2%). In a case clinically diagnosed as FMF, a new mutation called S145G (p. Ser145Gly, c.433A > G) was identified in exon 2 of the MEFV gene. Besides, addition of a new pathogenic MEFV variant to the literature, the relationship between the FMF clinic and homozygous form of R202Q, which was previously considered as a polymorphism, was highlighted.

Association between familial Mediterranean fever and multiple sclerosis: A case series from the JIR cohort and systematic literature review

INTRODUCTION

Familial Mediterranean fever (FMF) is the most frequent monogenic autoinflammatory disorder; and leads to the uncontrolled production of interleukin (IL)-1β. Multiple sclerosis (MS) is an inflammatory disease of the central nervous system; and its development seems to be partly correlated with IL-1β levels. It is hypothesized that FMF could be associated with MS. We aim to describe the features of patients displaying both diseases and to investigate the MEFV mutation rate in MS patients.

METHODS

Patients with definite MS were retrieved from the cohort of FMF patients in the Reference Center for Rare Auto-inflammatory Diseases and Amyloidosis (CEREMAIA). We also performed a systematic literature review of articles from PubMed that were published from 1990 to 2020.

RESULTS

Twenty-four patients were included in the case series: five patients (1.3%) from our cohort of 364 and 19 patients from the literature. The sex ratio was 2:1. The mean age at diagnosis of FMF was 19 years old; and that for MS was 29 years old. Seven studies investigating the MEFV mutation rate in MS patients were included. Three studies found a higher mutation rate in MS patients than in the control group.

CONCLUSION

FMF and MS features were comparable to those of patients with unrelated diseases; and MEFV mutation carriage was not positively correlated with MS. However; MS prevalence in FMF patients was higher than was expected in a healthy population. To a lesser extent; FMF prevalence in MS patients was higher than expected in a healthy population and the difference might not be significant. These data suggest that FMF could be associated with MS; and further studies are needed to investigate a potential causal association.

Prevalence of MEFV gene mutations in a large cohort of patients with suspected familial Mediterranean fever in Central Anatolia

BACKGROUND

Familial Mediterranean fever (FMF), an autosomal recessive, autoinflammatory disease that is common in Arabs, Jews, Armenians and Turks, is caused by mutations in the MEFV gene, which encodes a protein called pyrin. The disease is characterised by recurrent fever, peritonitis, pleuritis, abdominal pain and arthralgia.

OBJECTIVE

Determine the distributions of MEFV mutations and their relationship with clinical manifestations.

DESIGN

Retrospective, descriptive.

SETTING

Turkish community.

SUBJECTS AND METHODS

The study included patients with complaints related to FMF who were admitted to the research hospital of Cumhuriyet University between 2005 and 2017. FMF was diagnosed by physical examination using the Tel-Hashomer criteria. MEFV mutations were detected by reverse hybridization strip assay and pyrosequencing.

MAIN OUTCOME MEASURE

The prevalence of specific MEFV gene mutations in a large cohort of Middle Anatolia.

SAMPLE SIZE

10 033 patients admitted, 1223 with confirmed mutations.

RESULTS

Of 1684 patients diagnosed by Tel-Hashomer criteria, mutation screening confirmed that 1223 patients (72.6%) had FMF. Male/female ratio of the FMF patients was 1.3:1. One or more FMF mutations were found in 4497 patients (44.8%). 3262 had heterozygous or carrier mutations, 821 had compound heterozygous mutation, 381 had homozygous mutations, and 21 had triple mutations. Sixty-six percent had a family history of the disease and 13.7% of the patients had parental consanguinity. Main symptoms found in the patients were abdominal pain (85.2%), fever (84%), chest pain (30.2%), arthralgia (28.6%), rash or erysipelas-like erythema (8.2%). The most common mutation in this population was M694V (39%) of 5753 alleles.

CONCLUSION

M694V was the most frequent mutation in our population (Middle Anatolia, Turkey) and cause severe forms of the disease. Patients with E148Q, V726A and R761H mutations may have milder FMF symptoms. There was a high rate of carriers in our study group.

LIMITATIONS

Amyloidosis, an important complication of the disease, needs to be analyzed.

CONFLICT OF INTEREST

None.

Lack of clear and univocal genotype-phenotype correlation in familial Mediterranean fever patients: A systematic review

Familial Mediterranean fever (FMF) is the most common autosomal recessive autoinflammatory disease. To date, following the isolation of more than 280 MEFV sequence variants, the genotype-phenotype correlation in FMF patients has been intensively investigated; however, an univocal and clear consensus has not been yet reached. Thus, the aim of this systematic review was to analyze the available literature findings in order to provide to scientific community an indirect estimation of the impact of genetic factors on the phenotypic variability of FMF. This systematic review has been conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines. The p.M694V mutation was reported to have a relatively severe clinical course, similarly, patients homozygous for M694I and M680I, or carrying a combination of both at codons 694 and 680, have a severe disease. Also, patients homozygous for M694V and V726A variants experienced more severe clinical picture. Conversely, heterozygous p.V726A and p.E148Q genotypes have been correlated with a milder disease course. At present, doubts remain on the potential pathogenic role of E148Q variant. The heterogenity in clinical FMF manifestations reflects the changes occuring in repertoire of mutations. We believe that clinical criteria and gene tests, enhancing each other, could better support the diagnosis of FMF.

Frequency of familial Mediterranean fever (MEFV) gene mutations in patients with biopsy-proven primary glomerulonephritis

Primary glomerulopathies are those disorders that affect glomerular structure, function, or both in the absence of a multisystem disorder. We aimed to evaluate the frequency of MEFV gene mutation to show possible coexistence of FMF in patients diagnosed with biopsy-proven primary glomerulonephritis (GN). A total of 64 patients with biopsy-proven primary GN were included in the study. MEFV gene mutations examined retrospectively. The mean age of patients was 39.6 ± 13.4 (range 18-69), 35 of patients were female and 29 of patients were male. Of the 64 patients, 17 were mesangial proliferative glomerulonephritis (MsPGN), 15 were IgA nephropathy (IgAN), 12 were membranous glomerulonephritis (MGN), 11 were focal segmental glomerulosclerosis (FSGS), three were membranous proliferative glomerulonephritis (MPGN), three were immune complex glomerulonephritis (ICGN), two were minimal change disease (MCD), and one was IgM nephropathy (IgMN). MEFV gene mutation was detected in 35.9% (23) of these patients. The most frequently detected mutations were E148Q and M694V. Twelve cases (18.75% of GN patients) with MEFV gene mutation were diagnosed as FMF phenotype I. The frequency of MEFV gene mutation was detected at a high rate of 35.9%. Further studies with larger populations are needed to clarify the importance of these mutations on clinical progression of glomerulonephritis.

Prevalence of common MEFV 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.

The MEFV gene pathogenic variants and phenotype-genotype correlation in children with familial Mediterranean fever in the Çanakkale population

The aim of the current study was to determine the frequency of the Mediterranean fever (MEFV) gene pathogenic variants in 60 children diagnosed with familial Mediterranean fever (FMF) and to compare the phenotype-genotype correlation. Genomic DNA was isolated by the spin-column method from peripheral blood samples (collected in vacutainers containing EDTA) and buccal smears. The MEFV gene profiles for the current FMF cohort were genotyped by pyrosequencing and direct Sanger sequencing techniques for the target pathogenic variants. The most prominent clinical symptoms were abdominal pain (53.4%), fever (23.4%) and arthritis (23.3%). Eighteen different pathogenic variants were identified and the most frequent were p.Met694Val (20.0%), p.Glu148Gln (13.3%), p.Met680 Ile (11.7%) and p.Arg202Gln (11.7%). Abdominal pain, fever and arthritis were the most common presenting clinical characteristics. Results showed that not only clinical characteristics, but also genotyping of the MEFV gene is needed to establish the correct diagnosis of FMF in children and other family members.

The Relationship between NALP3 and Autoinflammatory Syndromes

The nucleotide-binding domain, leucine-rich repeat/pyrin domain-containing-3 (NALP3) inflammasome, which is required for synthesis of interleukin-1β, has been implicated in the pathogenesis of several autoinflammatory syndromes. This review of the literature summarizes the interconnectedness of NALP3 inflammasome with some of these disorders. Familial Mediterranean fever results from a mutation in the Mediterranean fever (MEFV) gene, which encodes the pyrin protein. Previous study results suggest that pyrin suppresses caspase-1 activation, perhaps by competing for the adaptor protein, termed, pyrin domain of apoptosis/speck-like protein containing a caspase-recruitment domain (ACS) which therefore interferes with NALP3 inflammasome activation. The nucleotide-binding domain, leucine-rich repeat/pyrin domain-containing-3 (NALP3) inflammasome is constitutively activated in cryopyrin-associated periodic syndromes due to gain-of-function mutations resulting from point mutations within the neuronal apoptosis inhibitor protein/class 2 transcription factor/heterokaryon incompatibility/telomerase-associated protein-1 (NACHT) domain of the NALP3 protein. Pyogenic arthritis, pyoderma gangrenosum and acne (PAPA) syndrome is caused by mutations in the genes encoding proline-serine-threonine phosphatase interacting protein 1 (PSTPIP1). These PSTPIP1 mutants are thought to bind to pyrin causing an increase in the pyrin domain of apoptosis/speck-like protein containing a caspase-recruitment domain (ASC) pyroptosome assembly leading to procaspase-1 recruitment and therefore its activation. Hyperimmunoglublinemia D syndrome is caused by mevalonate kinase (MVK) deficiency, which may be affected by protein accumulation that leads to NALP3 inflammasome activation. Tumor necrosis factor receptor-associated periodic syndrome is associated with mutations in the tumor necrosis factor receptor superfamily, member 1A (TNFRSF1A) gene which decreases the level of soluble tumor necrosis factor receptor-1 (TNFR1) leading to neutralization of tumor necrosis factor (TNF)-α. In general, these autoinflammatory disorders have shown a clinical response to interleukin-1 (IL-1) antagonists, suggesting that the NALP3 inflammasome serves a critical role in their pathogenesis.

Prevalence of Fabry Disease in Familial Mediterranean Fever Patients from Central Anatolia of Turkey

Fabry disease (FD) is a progressive, X-linked inherited disorder of glycosphingolipid metabolism due to deficient or absent lysosomal alpha-galactosidase A (AGALA) activity. FD and familial Mediterranean fever (FMF) have typical clinical similarities, and both diseases may progress to end-stage renal diseases. In this study, we aimed to determine the prevalence of FD in patients with FMF from Central Anatolia of Turkey. The study group consisted of 177 FMF patients, followed up by the Adult and Pediatric Nephrology Clinic of Cumhuriyet University Hospital. Screening for AGALA activity was performed by the dry blood spot method. Mutation analysis for GLA gene was carried out for patients having an AGALA enzyme activity value lower than the normal reference value. Low AGALA activity was detected in 23 (13 %) patients. Heterozygous GLA gene mutation c.[937G>T] p.[D313Y] was detected in one female patient (0.56 %). The patient was a 53-year-old female with proteinuria and who had undergone left nephrectomy; her glomerular filtration rate (GFR) by scintigraphy was found to be 70 ml/min. She had M694V mutation and no clinical manifestation of FD. In our study, the prevalence rate of FD was found as 0.56 % in FMF patients. The similarities between the symptoms of FMF and FD might lead to a diagnostic dilemma in physicians at countries where FMF is observed frequently. Although the prevalence of FD is rare, physicians should keep in mind that FD has an ambiguous symptomology pattern of FMF.

Glutathione-S-Transferase Variants are not Associated With Increased Carotid Intima-Media Thickness in Turkish Familial Mediterranean Fever Patients

Objectives

This study aims to evaluate the carotid intima-media thickness (CIMT) in patients diagnosed with Familial Mediterranean fever (FMF) and investigate whether there is a relationship between glutathione-S-transferase (GST) gene polymorphisms and CIMT.

Patients and methods

Sixty FMF patients (17 males, 43 females; mean age: 31.43±11.36 years; range 18 to 45 years) and 60 healthy controls (22 males, 38 females; mean age: 29.8±5.82 years; range 18 to 40 years) were enrolled in this study. Polymerase chain reaction-restriction fragment length polymorphism methods were carried out to assess GST polymorphisms. CIMT was measured by carotid ultrasonography. Biochemical parameters were also evaluated using biochemical methods.

Results

Right and left CIMT of FMF patients were statistically significantly higher than that of control group (CIMT right p=0.001 and CIMT left: p=0.033). There was no significant association in terms of GST polymorphisms between FMF and control groups. No significant association was observed between GST polymorphisms and CIMT. Low density lipoprotein, erythrocyte sedimentation rate, and fibrinogen levels were significantly higher in the patient group (p<0.05). The difference between groups was not significant in terms of other biochemical parameters (p>0.05).

Conclusion

Although no significant association was observed between GST polymorphisms and CIMT in FMF patients and controls, CIMT was statistically significantly higher in FMF patients compared to controls.

Frequencies of the Common MEFV Gene Mutations in Adiyaman, Southeast Anatolia, Turkey

Familial Mediterranean fever (FMF) is an autosomal recessive disorder characterized by fever and serosal inflammation. The reasons for the disorder are mutations in the Mediterranean fever (MEFV) gene; the most common of which are M694V, M680I, M694I and V726A. In this study, we aimed to screen these common mutations of the MEFV gene and then determine the prevalence of FMF according to these mutations in Adıyaman, Southeast Anatolia, Turkey. Seven hundred and sixty-seven healthy individuals from the region of Adıyaman participated in the study. Polymerase chain reaction-amplification refractory mutation system (PCR-ARMS) methods were used to determine the common mutations of the MEFV gene. Twenty-six (3.9%) individuals had only one mutation in the MEFV gene, 25 individuals were heterozygous and one person was homozygous for the V726A mutation (0.15%). In the present study, the V726A mutation (50.0%) was the most frequent, followed by M694V (38.5%), M680I (7.7%) and M694I (3.8%). It was seen that the carrier rate was very low and the prevalence of FMF was 0.15%, according to the common mutations of the MEFV gene in Adıyaman, Southeast Anatolia, Turkey.

Bcıı--RFLP profiles for serum amiloid A1 and mutated MEFV gene prevalence in chronic renal failure patients requiring long-term hemodialysis

BACKGROUND AND AIM

There is an increased mortality risk in long-term hemodialysis patients of renal failure due to the chronic inflammation. The relationship between the chronic renal failure (CRF) and the role of familial genetic markers remains incompletely understood. In the current study, it was aimed to find out the prevalence of common MEFV gene mutations and BcII polymorphism in serum amyloid A1 (SAA1) gene in chronic renal patients (CRF) who require long-term hemodialysis.

METHOD

Current cohort includes 242 CRF patients and 245 healthy individuals from the same population. Total genomic DNA was isolated from peripheral blood-EDTA samples and genotyping of target MEFV gene was carried out by reverse hybridization Strip Assay and real-time techniques. The SAA1 gene was genotyped by the BclI-RFLP method.

RESULTS

Increased mutated MEFV genotypes were found in current CRF patients when compared with the control group from the same ethnicity and the difference was statistically significant (Table 2) (OR: 4.9401, 95% CI: 3.0694-7.9509), p<0.0001. The most frequent point mutations were M694V and E148Q. The mutated T allel frequency in the SAA1 gene was also different when compared with the healthy controls and the difference was found to be statistically significant (χ2: 13.18; p=0.000).

CONCLUSIONS

The current results indicate the germ-line mutations in both genetic biomarkers (MEFV and SAA1 genes) that are related to inflammation and amyloidosis processes may play a crucial role in CRF pathogenesis due to the long-term chronic inflammation.

The role of IL-4 gene 70 bp VNTR and ACE gene I/D variants in Familial Mediterranean fever

Familial Mediterranean fever (FMF) is characterized by recurrent attacks of fever and inflammation in the peritoneum, synovium, or pleura, accompanied by pain. It is an autosomal recessive disease caused by mutations in the MEFV (MEditerranean FeVer) gene. Patients with similar genotypes exhibit phenotypic diversity. As a result, the variations in different genes could be responsible for the clinical findings of this disease. In previous studies genes encoding Angiotensin-Converting Enzyme (ACE) and IL-4 (Interleukin-4) were found to be associated with rheumatologic and autoimmune diseases. In the present study we hypothesized whether ACE I/D or IL-4 70 bp variable tandem repeats (VNTR) genes are associated with FMF and its clinical findings in Turkish patients. Genomic DNA obtained from 670 persons (339 patients with FMF and 331 healthy controls) was used in the study. Genotypes for an ACE gene I/D polymorphism and IL-4 gene 70 bp VNTR were determined by polymerase chain reaction with specific primers. To our knowledge, this is the first study examining ACE gene I/D polymorphism and IL-4 gene 70 bp VNTR polymorphism in FMF patients. As a result, there was a statistically significant difference between the groups with respect to genotype distribution (p<0.001). According to our results, ACE gene DD genotype was associated with an increased risk in FMF [p<0.001; OR (95%): 7.715 (4.503-13.22)]. When we examined ACE genotype frequencies according to the clinical characteristics, we found a statistically significant association between DD+ID genotype and fever (p=0.04). In addition IL-4 gene P1P1 genotype was associated with FMF (p<0.001). We propose that D allele or DD genotype of ACE gene and P1 allele or P1P1 genotype of IL-4 gene may be important molecular markers for susceptibility of FMF.

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 Kırıkkale 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.

Prevalence of known mutations and a novel missense mutation (M694K) in the MEFV gene in a population from the Eastern Anatolia Region of Turkey

Familial Mediterranean fever (FMF) is an autosomal recessive disorder characterized by recurrent attacks of fever and serositis. Mutations in the Mediterranean fever gene (MEFV) localized on the short arm of chromosome 16 cause FMF. Over 90 MEFV missense/nonsense mutations have been identified so far in FMF patients, mostly in the 10th exon of the gene. In this study, the molecular test results of 891 patients identified as having FMF clinical symptoms referred to Molecular Genetics Laboratory of the Department of Medical Biology and Genetics, Faculty of Medicine, Inonu University, Malatya/Turkey were retrospectively evaluated. Patients were referred by their physicians for MEFV mutation detection. The DNA fragments including hot spots within the coding sequences of the MEFV gene were amplified by PCR using genomic DNA and analyzed by pyrosequencing technique. Of the 891 patients investigated, 420 (47.13%) had at least one mutation. The most frequent mutation was E148Q, followed by M694V, M680I (G/C), P369S, V726A, R761H, A744S, M694I, K695R and F479L mutations. In addition, a novel missense mutation (M694K) was reported in seven members of a family in the course of mutation screening of patients.

Evaluating MEFV 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).

Association between ABCB1 (MDR1) gene 3435 C>T polymorphism and colchicine unresponsiveness of FMF patients

The multidrug resistance gene-1 (MDR1, adenosine triphosphate-binding cassette transporter: ABCB1, P-glycoprotein) encodes membrane proteins that play a crucial role in protecting cells from xenobiotics, chemicals, and drugs. The TT genotype of 3435 codon in exon 26 of MDR1 gene causes overexpression of gene activity and effluxes many chemically diverse compounds across the plasma membrane. We studied the association between C3435T polymorphisms (single nucleotide polymorphism) of MDR1 gene and colchicine-resistant familial Mediterranean fever (FMF) patients. Total genomic DNA samples from 52 FMF patients of colchicine unresponsiveness were used for FMF (MEFV) and MDR1 genes profile analyses. Target genes were genotyped by multiplex PCR-based reverse-hybridization Strip Assay method. The preliminary current results showed increased T allele frequency (0.596) in colchicine unresponsiveness of FMF patients. The distributions of the CC, CT, and TT genotypes in colchicine nonresponder FMF patients were 17%, 46%, and 37%, respectively. Our results indicate that C3435T polymorphism in exon 26 of MDR1 gene is associated with colchicine resistance in nonresponder FMF patients during the common therapy protocol.

Enhanced exon 2 skipping caused by c.910G>A variant and alternative splicing of MEFV genes in two independent cases of familial Mediterranean fever

Most reported cases of familial Mediterranean fever (FMF) involve missense mutations of MEFV concentrated within exon 10. We experienced two independent pedigrees of a unique variant in the MEFV gene that might cause excessive exon 2 skipping due to enhanced alternative splicing. In this study, we tried to elucidate the molecular mechanism of the MEFV variant as a cause of the FMF phenotype. Peripheral blood was obtained from volunteers and two patients with homozygous c.910G>A variant of the MEFV gene. MEFV messenger RNA (mRNA) expression patterns in mononuclear cells and granulocytes were compared using forward and reverse primers from exons 1 and 3, respectively. Expression profiles of pyrin were examined by transfecting wild-type and variant MEFV genes into HEK293T cells. Expression of normal-sized mRNA was extremely reduced in these patients, whereas that of aberrant short mRNA, deleting exon 2 (Δex2), was significantly increased. Immunohistochemical and immunoblotting analyses revealed a truncated immunoreactive pyrin protein in cells transfected with Δex2 cDNA. The MEFV gene c.910G>A variant results in accelerated aberrant splicing with abnormal protein size, presumably leading to anomalous pyrin function. This is the first report to show that an MEFV variant other than missense mutation is responsible for the FMF phenotype.