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).     

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.

     

<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.     

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.     

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.     

<Emphasis Type="Italic">MEFV</Emphasis> heterogeneity in Turkish Familial Mediterranean Fever patients

Turkey is one of the few countries in the world where Familial Mediterranean Fever (FMF), an autoinflammatory disease caused by mutations in MEFV, the gene encoding pyrin, is not rare. Many interesting studies regarding the genetics of Familial Mediterranean Fever in Turkey have been already published. Despite that different MEFV genetic profiles have been revealed for Turkish FMF patients, deriving from different regions of Turkey, a systematic population genetics analysis has not been carried out yet. The present study aims to investigate the population genetics of MEFV in Turkish FMF patients so as to additionally facilitate the clinical interpretation of individualized genetic data. All relevant studies have been recruited by searching PubMed with the terms “MEFV”, “FMF”, and “Turkey”. Seven of them, including 3,061 FMF patients, contained all necessary data concerning allelic and genotypic frequencies of the 4 commonest MEFV mutations in Turkey (M694V, V726A, M680I, E148Q). From all 6,122 MEFV alleles analyzed, the M694V mutation was recognized in 15.6–52.2% (mean 29.3%), the V726A in 1.5–9.7% (mean 4.8%), the M680I in 1.5–15.5% (mean 7.6%), and the E148Q in 3.2–13.9% (mean 5.5%). Unidentified mutations ranged from 0–42.9% (mean 16.8%). No mutations were found in 0–54.5% (mean 36.0%) of the patients. The allelic and genotypic frequencies of the most frequent mutation (M694V) showed aberration of the Hardy–Weinberg law for all 7 populations studied. By application of the Arlequin 2.0 population genetics software, the Fixation index (F _ST) was found to be 0.09994, thus demonstrating that the observed variability is mainly within (90.006%) and not among (9.994%) populations (P < 0.00001). Moreover, the global test of differentiation demonstrated that every population differs from each other (P < 0.00325). Finally, the Ewens–Watterson test of selective neutrality yielded to statistical significance in only 3 populations. In conclusion, Turkish FMF patients are characterized by an increased genetic heterogeneity, explained by the intrapopulation differentiation. Thus, the regional origin should be regarded as a determining factor in the diagnosis of FMF in Turkish patients.     

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.     

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.     

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.     

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.     

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.     

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.     

Significance of MEFV gene R202Q polymorphism in Turkish familial Mediterranean fever patients

Objective

Familial Mediterranean fever (FMF) is an autosomal recessive disorder characterized by recurrent attacks of fever and inflammation in the peritoneum, synovium, or pleura, accompanied by pain. The disease is associated with mutations in the Mediterranean fever (MEFV) gene, which encodes for the pyrin protein. The aim of this study was to explore the frequency and clinical significance of the R202Q (c.605G>A) polymorphism in exon 2 of the MEFV gene in a cohort of Turkish patients with FMF.

Methods

The study included 191 patients with FMF and 150 healthy controls. Genomic DNA was isolated and genotyped using polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) assay for the MEFV gene R202Qpolymorphism.

Results

The genotype and allele frequencies of R202Q polymorphism showed a statistically significant difference between FMF patients and controls (p < 0.0001 and p = 0.0004, respectively) and especially the homozygous AA genotype was significantly higher in FMF patients than healthy controls (p = 0.0002; odds ratio = 6.27; 95% CI = 2.1–18.3). However no significant association was observed between clinical and demographic features of FMF patients and R202Qpolymorphism.

Conclusion

The results of this study showed that there was a high association between MEFV gene R202Q polymorphism and FMF. R202Q polymorphism should be included in routine molecular diagnosis of FMF patients.     

The Contribution of SAA1 Polymorphisms to Familial Mediterranean Fever Susceptibility in the Japanese Population

Background/Aims

Familial Mediterranean Fever (FMF) has traditionally been considered to be an autosomal-recessive disease, however, it has been observed that substantial numbers of patients with FMF possess only 1 demonstrable MEFV mutation. The clinical profile of familial Mediterranean fever (FMF) may be influenced by MEFV allelic heterogeneity and other genetic and/or environmental factors.

Methodology/Principal Findings

In view of the inflammatory nature of FMF, we investigated whether serum amyloid A (SAA) and interleukin-1 beta (IL-1β) gene polymorphisms may affect the susceptibility of Japanese patients with FMF. The genotypes of the -13C/T SNP in the 5′-flanking region of the SAA1 gene and the two SNPs within exon 3 of SAA1 (2995C/T and 3010C/T polymorphisms) were determined in 83 Japanese patients with FMF and 200 healthy controls. The same samples were genotyped for IL-1β-511 (C/T) and IL-1 receptor antagonist (IL-1Ra) variable number of tandem repeat (VNTR) polymorphisms. There were no significant differences between FMF patients and healthy subjects in the genotypic distribution of IL-1β -511 (C/T), IL-1Ra VNTR and SAA2 polymorphisms. The frequencies of SAA1.1 allele were significantly lower (21.7% versus 34.0%), and inversely the frequencies of SAA1.3 allele were higher (48.8% versus 37.5%) in FMF patients compared with healthy subjects. The frequency of -13T alleles, associated with the SAA1.3 allele in the Japanese population, was significantly higher (56.0% versus 41.0%, p = 0.001) in FMF patients compared with healthy subjects.

Conclusions/Significance

Our data indicate that SAA1 gene polymorphisms, consisting of -13T/C SNP in the 5′-flanking region and SNPs within exon 3 (2995C/T and 3010C/T polymorphisms) of SAA1 gene, are associated with susceptibility to FMF in the Japanese population.     

Evidence of digenic inheritance in autoinflammation-associated genes

Familial Mediterranean fever (FMF) has traditionally been considered as a monogenic autosomal recessive disorder caused by mutations in the MEFV gene with highest incidence among Mediterranean populations. In a considerable number of patients with typical FMF, only one MEFV mutation was identified and the possibility that more than one autoinflammatory gene may be responsible for their disease was investigated. In the present study, an extensive search for possible mutations in three hereditary recurrent fever (HRF) genes was performed in 128 MEFV heterozygous Greek–Cypriots clinically diagnosed based on their phenotype with FMF-like disease from a previous study. Sequence analysis was performed for MVK, TNFRSF1A and NLRP3 genes which is also known to cause HRFs. In total, three patients were identified with heterozygous mutations and a second mutation in an autoinflammatory gene. Two patients carried a MEFV mutation and a NLRP3 mutation, and an additional third carried a MEFV mutation and a TNFRSF1A mutation. Patient 1 carried MEFV p.[Val726Ala] (NM_000243.2:c.2177T >C) and NLRP3 p.[Val198Met] (NM_001243133.1:c.592G >A) variants and patient 2 carried MEFV p.[Glu148Gln] (NM_000243.2:c.442G >C) variant which is of uncertain significance and NLRP3 p.[Arg176Trp] (NM_001243133.1:c.526C >T). Lastly, patient 3 was identified to carry MEFV p.[Met694Val] (NM_000243.2:c.2080A >G) and TNFRSF1A p.[Arg121Gln] (NM_001065.3:c.362G >A) variants. The results from this study indicate that screening of genes known to cause HRFs in patients already identified with a single MEFV mutation, can reveal quite rare but potentially causative mutational combinations at different loci. Such interaction provide further evidence for possible locus–locus interactions and phenotypes resulting from digenic inheritance.     

Inflammation in Mice Ectopically Expressing Human Pyogenic Arthritis,Pyoderma Gangrenosum,and Acne (PAPA) Syndrome-associated PSTPIP1 A230T Mutant Proteins

Pyogenic Arthritis, Pyoderma Gangrenosum, and Acne Syndrome (PAPA syndrome) is an autoinflammatory disease caused by aberrant production of the proinflammatory cytokine interleukin-1. Mutations in the gene encoding proline serine threonine phosphatase-interacting protein-1 (PSTPIP1) have been linked to PAPA syndrome. PSTPIP1 is an adaptor protein that interacts with PYRIN, the protein encoded by the Mediterranean Fever (MEFV) gene whose mutations cause Familial Mediterranean Fever (FMF). However, the pathophysiological function of PSTPIP1 remains to be elucidated. We have generated mouse strains that either are PSTPIP1 deficient or ectopically express mutant PSTPIP1. Results from analyzing these mice suggested that PSTPIP1 is not an essential regulator of the Nlrp3, Aim2, or Nlrc4 inflammasomes. Although common features of human PAPA syndrome such as pyogenic arthritis and skin inflammation were not recapitulated in the mouse model, ectopic expression of the mutant but not the wild type PSTPIP1 in mice lead to partial embryonic lethality, growth retardation, and elevated level of circulating proinflammatory cytokines.     

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.     

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.     

Identification of Disease-Promoting HLA Class I and Protective Class II Modifiers in Japanese Patients with Familial Mediterranean Fever

ObjectivesThe genotype-phenotype correlation of MEFV remains unclear for the familial Mediterranean fever (FMF) patients, especially without canonical MEFV mutations in exon 10. The risk of FMF appeared to be under the influence of other factors in this case. The contribution of HLA polymorphisms to the risk of FMF was examined as strong candidates of modifier genes.MethodsGenotypes of HLA-B and -DRB1 loci were determined for 258 mutually unrelated Japanese FMF patients, who satisfied modified Tel-Hashomer criteria, and 299 healthy controls. The effects of carrier status were evaluated for the risk of FMF by odds ratio (OR). The HLA effects were also assessed for clinical forms of FMF, subsets of FMF with certain MEFV genotypes and responsiveness to colchicine treatment.ResultsThe carriers of B*39:01 were increased in the patients (OR = 3.25, p = 0.0012), whereas those of DRB1*15:02 were decreased (OR = 0.45, p = 0.00050), satisfying Bonferroni’s correction for multiple statistical tests (n = 28, p<0.00179). The protective effect of DRB1*15:02 was completely disappeared in the co-existence of B*40:01. The HLA effects were generally augmented in the patients without a canonical MEFV variant allele M694I, in accordance with the notion that the lower penetrance of the mutations is owing to the larger contribution of modifier genes in the pathogenesis, with a few exceptions. Further, 42.9% of 14 colchicine-resistant patients and 13.5% of 156 colchicine-responders possessed B*35:01 allele, giving OR of 4.82 (p = 0.0041).ConclusionsThe differential effects of HLA class I and class II polymorphisms were identified for Japanese FMF even in those with high-penetrance MEFV mutations.     

A High-Resolution Genetic Map of the Familial Mediterranean Fever Candidate Region Allows Identification of Haplotype-Sharing among Ethnic Groups

Familial Mediterranean fever (FMF) is a recessive disorder of inflammation caused by mutations in a gene (designatedMEFV) on chromosome 16p13.3. We have recently constructed a 1-Mb cosmid contig that includes the FMF critical region. Here we show genotype data for 12 markers from our physical map, including 5 newly identified microsatellites, in FMF families. Intrafamilial recombinations placedMEFVin the ∼285 kb betweenD16S468/D16S3070andD16S3376.We observed significant linkage disequilibrium in the North African Jewish population, and historical recombinants in the founder haplotype placedMEFVbetweenD16S3082andD16S3373(∼200 kb). In smaller panels of Iraqi Jewish, Arab, and Armenian families, there were significant allelic associations only forD16S3370andD16S2617among the Armenians. A sizable minority of Iraqi Jewish and Armenian carrier chromosomes appeared to be derived from the North African Jewish ancestral haplotype. We observed a unique FMF haplotype common to Iraqi Jews, Arabs, and Armenians and two other haplotypes restricted to either the Iraqi Jewish or the Armenian population. These data support the view that a few major mutations account for a large percentage of the cases of FMF and suggest that some of these mutations arose before the affected Middle Eastern populations diverged from one another.