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

OBJECTIVE: Familial Mediterranean fever (FMF) is an autosomal-recessive disorder characterized by recurrent attacks of fever, with abdominal, thoracic, or articular pain. FMF is particularly common in Mediterranean populations, while other populations are rarely affected. MEFV gene analysis provides the only objective diagnostic criterion for FMF. However, the spectrum of MEFV mutations, which was first established in classically affected populations, remains insufficiently studied in other populations. The purpose of this study was to assess involvement of MEFV in the phenotype of western European Caucasian patients with a clinical diagnosis of FMF. METHODS: Mutation analysis was performed in 208 Caucasian patients from western Europe, by screening for the most common MEFV mutations in exons 2, 3, 5, and 10, and by sequencing the promoter region and the whole MEFV coding sequence in 21 of these patients. RESULTS: None of the patients carried 2 mutated alleles. Only 2 patients carried 1 mutated allele. CONCLUSION: FMF-like syndromes in western European Caucasian populations cannot be explained by MEFV mutations. These results should be helpful in avoiding laborious and costly MEFV molecular analyses that, at the population level, seem to be of poor diagnostic value in the case of western European Caucasian patients, and rather should prompt a search for other causes in those patients.     

Familial Mediterranean Fever: Genotype-Phenotype Correlations in Japanese Patients

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

Amyloidosis induced, end stage renal disease in patients with familial Mediterranean fever is highly associated with point mutations in the MEFV gene

BACKGROUND: Familial Mediterranean fever (FMF) is an autosomal recessive disease characterised by recurrent attacks of fever and serositis. Amyloidosis is the most significant complication of FMF, leading to end stage renal disease (ESRD). Recently the gene (MEFV) causing this disease was cloned and more than 18 mutations have been identified. The hypothesis that the development of amyloidosis is associated with one of these mutations was tested. METHODS: 23 patients with FMF and ESRD were analysed for their MEFV mutations and correlated with their corresponding rectal and renal biopsies. As case controls 23 patients with FMF free of renal disease, but with similar origin, sex, age, and age at onset of FMF, were chosen. RESULTS: All the patients with ESRD induced by amyloidosis were homozygous for the M694V or M694I mutations. This finding was significantly different from that seen in the control group. CONCLUSIONS: Amyloidosis is highly associated with the 694 substitution in the MEFV gene causing FMF. It seems that genetic predisposition plays a part in the development of this complication of FMF.     

MEFV mutation analysis of familial Mediterranean fever in Japan

BACKGROUND: Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of fever with serosal inflammation. FMF gene (MEFV) mutations have been identified primarily in patients from Mediterranean populations. Although several clinical cases have been reported in Japan, there have been few reports to date on mutation analysis. We studied FMF patients and their relatives to examine the clinical and genetic features of this disease in the Japanese population. METHODS: Twelve Japanese FMF patients who met the Tel Hashomer criteria and a total of 17 relatives from 5 of 10 families underwent molecular genetic studies to detect MEFV mutations. The characteristics of these Japanese FMF patients and geno-phenotypical correlations were examined. RESULTS: Almost all of our patients had been suffering for a long time from fever of unknown origin and one patient also had systemic amyloidosis. In our 12 FMF patients, we detected the substitutions E84K, L110P, E148Q, R761H and M694I. We also newly diagnosed 2 relatives as having FMF based on clinical symptoms and the existence of FMF mutations. One patient was homozygous for E148Q, the patient with systemic amyloidosis was a homozygote for M694I and 4 patients from 3 families were compound heterozygotes for E148Q and M694I. Three patients in one family were compound heterozygotes for E148Q, L110P and M694I. There were 3 patients who were heterozygous for E84K, L110P-E148Q or M694I and had no other nucleotide changes in the exons of MEFV. On the other hand, 2 relatives who had never experienced symptoms of FMF were homozygous for L110P-E148Q as well as compound heterozygous for E148Q/E148Q-R761H. E148Q and M694I were the most frequently detected substitutions in our study. CONCLUSIONS: MEFV mutations occur in Japanese FMF patients though FMF is rare in Japan. The identification of MEFV mutations could be a reliable diagnostic test for FMF. The results of genetic analyses on 14 Japanese FMF patients in this study revealed that E148Q and M694I are frequent alleles.     

The familial Mediterranean fever (MEVF) gene as a modifier of Crohn's disease

OBJECTIVES: Crohn's disease (CD) has been reported to be more frequent among non-Ashkenazi Jewish patients suffering from familial Mediterranean fever (FMF). Interestingly, functional similarities between the CD susceptibility gene (NOD2/CARD15) and the FMF gene (MEFV) have been described: both belong to the death domain containing protein family, important in the regulation of apoptosis, cytokine processing and inflammation. AIMS: To investigate the prevalence of MEFV mutations in Jewish non-Ashkenazi CD patients and its putative effect on CD presentation. METHODS: Germline DNA of 105 Israeli CD patients of non-Ashkenazi and mixed Ashkenazi-non-Ashkenazi ethnic background was analyzed for three most common MEFV mutations: M694V, V726A, and E148Q. Five patients (4.7%) with a clinical diagnosis of FMF were included. Data obtained from each patient included: age of onset, disease location, and behavior, the presence of extraintestinal manifestations of CD and therapeutic regimens. RESULTS: The overall prevalence of mutation carriers among non-FMF-CD patients was 13% (13/100). A stricturing disease pattern was observed in 56% (10/18) of all carriers, FMF-CD, and non-FMF-CD patients, and in 25% (22/87) of noncarriers (OR: 3.7, 95% CI: 1.3-10.5, p= 0.015). The prevalence of fistulas was comparable in both groups. Extraintestinal manifestations were significantly more frequent among carriers than noncarriers (65%vs 32%, OR 3.9, 95% CI = 1.3-11.5, p= 0.015). No differences were observed in disease location and disease severity. CONCLUSIONS: MEFV mutations are not associated with CD susceptibility, yet the presence of these mutations appears to be associated with a stricturing disease pattern and extraintestinal disease manifestations of CD.     

Mediterranean fever (MEFV) gene mutation frequency is not increased in adults with rheumatic heart disease

It is well established that there are people with higher risk of developing acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Mediterranean fever (MEFV) gene mutations might be one of the genetic predisposition factors in the development of ARF/RHD since defect in familial Mediterranean fever (FMF) patients is proposed to be heightened inflammatory response to certain stimuli. Previous clinical observations suggested a relationship between FMF and ARF/RHD. The aim of this study was to investigate the role of the MEFV gene mutations in the susceptibility to RHD in Turkish patients. A total of 100 patients with RHD and 100 healthy controls were included in the study. Diagnosis of RHD was based on echocardiographic findings in which a predominant mitral stenosis was used as an inclusion criterion. Genetic analysis was carried out by sequence analysis investigating two hot spots (exons 2 and 10) for MEFV mutations. Mutation analysis showed that 22 RHD patients (22%) and 24 healthy controls (24%) carried at least one mutated allele. MEFV mutations were identified in 22 of 200 (11%) chromosomes in RHD patients while 26 of the 200 (13%) chromosomes of healthy controls were found to carry a mutated allele. No difference was found in allele frequencies and their distribution between the patients and healthy controls (p = 0.54). MEFV mutations are not associated with a predisposition to develop RHD in adult Turkish patients.     

Common FMF alleles may predispose to development of Behcet's disease with increased risk for venous thrombosis

BACKGROUND: Behcet's disease (BD) is an inflammatory disorder of unknown cause, associated with vasculitis. Arterial or venous thrombosis occurs in about 25% of BD patients. Familial Mediterranean fever (FMF) is another inflammatory disorder, which stems from mutations in the FMF gene (MEFV) and shares a number of features with BD. OBJECTIVE: MEFV analysis in patients with BD suggests that mutated MEFV may act as a susceptibility gene in BD. We studied the rate and the clinical correlates of MEFV mutations in Israeli BD patients. METHODS: Included were 54 BD patients who satisfied the International Study Group criteria for BD. All BD patients were genotyped using polymerase chain reaction (PCR) and restriction enzyme analysis for the three most common MEFV mutations (M694V, V726A, and E148Q). The association between BD manifestations and MEFV alleles was analysed. RESULTS: Twenty-one BD patients were found to carry a single MEFV mutation and three additional patients were compound heterozygotes, a frequency significantly higher than that expected for ethnically matched healthy individuals. There were no statistically significant differences between carriers and non-carriers with respect to gender, frequency of HLA B5 antigen, cutaneous lesions, joint disease, and severity score. However, carriers did experience thrombosis more often [54% vs. 17%, p<0.005, odds ratio (OR) = 6.9, 95% confidence interval (CI) 1.75-26.9] and uveitis less often (20% vs. 40%, p<0.05, OR = 0.2, 95% CI 0.04-0.92). CONCLUSIONS: MEFV appears to be a susceptibility and modifier gene in BD.     

MEFV gene is a probable susceptibility gene for Behçet's disease

OBJECTIVE: Beh?et's disease (BD) is a rare, chronic, multisystem inflammatory disorder. The prevalence of BD is higher in the Middle Eastern and Mediterranean populations. Another chronic inflammatory disease, familial Mediterranean fever (FMF), is also known to be highly prevalent in these populations. The prevalence of BD is higher in the FMF patient population than in populations known to be rich in BD . Both BD and FMF have some pathophysiological features in common and they result from inappropriate activation of neutrophils. Clinical manifestations of both diseases can mimic each other and the coexistence of both diseases in the same patient has been reported. Given that BD and FMF have similar pathophysiological, epidemiological, and clinical features, we hypothesized that the gene responsible for FMF, MEFV, may also play a role in the pathogenesis of BD. METHODS: Forty-two BD patients who had no symptoms and family history for FMF and 66 healthy controls were screened for common MEFV gene mutations (E148Q, M680I, M694V, and V726A). RESULTS: Fifteen patients (36%) displayed MEFV mutations (nine M694V, five E148Q, and one M680I) and mutation rates were significantly elevated compared to 66 (11%) healthy controls (p = 0.0034). CONCLUSION: The occurrence of frequent MEFV mutations in BD patients suggests that the MEFV gene is involved in the pathogenesis of Beh?et's disease.     

Familial mediterranean fever and Behçet's disease--are they associated?

OBJECTIVE: To test whether the coexistence of familial Mediterranean fever (FMF) and Beh?et's disease (BD) is more frequent than expected and whether each disease affects the severity of the other. METHODS: We screened 353 charts of patients with FMF to detect individuals with concomitant BD. Of these, 152 patients with FMF over the age of 18 years were also interviewed and examined specifically. We also studied 53 patients with BD, looking for FMF and for their MEFV mutations. We compared BD patients with MEFV mutations to those without them. RESULTS: None of 353 patients with FMF was found to have concomitant BD. Sixteen patients with BD bore MEFV mutations, 2 of whom were symptomatic homozygotes and had concomitant FMF. No patient with BD with a single MEFV mutation had FMF. Both BD groups (with or without MEFV mutations) were similar in their clinical manifestations and disease course. CONCLUSION: BD and FMF are 2 separate entities that have a mild trend toward a higher than expected association. However, there was no mutual effect of FMF on BD or vice versa.     

An unexpectedly high frequency of MEFV mutations in patients with anti-citrullinated protein antibody-negative palindromic rheumatism

OBJECTIVE: To investigate whether the MEFV gene, which is involved in the regulation of the inflammatory response and has been associated with familial Mediterranean fever (FMF) and intermittent hydrarthrosis, is implicated in the pathogenesis of palindromic rheumatism (PR) and to examine its clinical presentation and its evolution in a Spanish cohort of PR patients. METHODS: Family histories, demographic clinical data, and laboratory characteristics of 75 patients diagnosed as having PR were collected from medical records and personal interviews. The healthy control group included 325 blood bank donors. The FMF control group was made up of 84 Spanish FMF patients. Genomic DNA was isolated, and MEFV gene mutation analysis was performed by polymerase chain reaction amplification and sequence analysis. RESULTS: Sixty-five unrelated PR patients were finally included in the study. MEFV gene mutation analysis identified 8 of these 65 patients (12.3%) as carriers of at least 1 mutated MEFV allele. Patients with MEFV mutations had higher mean age and age at disease onset, but lower mean serum levels of anti-citrullinated protein antibodies (ACPAs). No other significant differences were observed between patients with and those without mutations. The frequency of MEFV mutations in ACPA-negative PR patients was 22.2%, compared with 5.3% in ACPA-positive PR patients (P = 0.058). CONCLUSION: This study shows a previously unreported high prevalence of mutations of the MEFV gene in patients with ACPA-negative PR. This supports the hypothesis that it might be a susceptibility gene. Our findings also support the hypothesis that the MEFV gene might participate in the pathogenesis of other undifferentiated relapsing inflammatory rheumatic disorders.     

The MICA region determines the first modifier locus in familial Mediterranean fever

OBJECTIVE: Familial Mediterranean fever (FMF) is a genetically recessive inflammatory disease caused by mutations in the MEFV gene. Most patients of non-Ashkenazi Jewish ancestry or those who are homozygous for M694V manifest a severe disease course, but some express a mild form of the disease. We therefore searched for other genes which could possibly be implicated in the disease phenotype. We tested MICA (major histocompatibility complex class I chain-related gene A) because it has been associated with a number of other inflammatory disorders. METHODS: One hundred fifty FMF probands and their family members were evaluated. The MEFV gene was screened by a combination of denaturing gradient-gel electrophoresis, restriction fragment length polymorphism, and amplification refractory mutation system. The MICA transmembrane polymorphism in exon 5 was analyzed after biotin-labeled polymerase chain reaction products were loaded onto sequencing gels and subjected to autoradiography. RESULTS: The contribution of MICA to the FMF phenotype was confirmed after adjustment for the patient's ancestry and for the MEFV genotype. MEFV was individually the most important prognostic factor for the disease. However, the impact of M694V homozygosity on the age at disease onset (OR 2.3) was aggravated if patients also inherited MICA-A9 (OR 6.3). In contrast, the frequency of attacks was found to be dramatically reduced (OR 0.16) in patients with MICA-A4. CONCLUSION: We have identified the first FMF modifier locus, MICA. FMF is the first model of a Mendelian disease associated with MICA. These results clarify, at least partly, the inconsistent phenotype-MEFV correlation in FMF.     

Common MEFV mutation analysis in Iranian Azeri Turkish patients with familial Mediterranean fever

OBJECTIVES: To identify the frequency and distribution of familial Mediterranean fever (FMF) gene (MEFV) mutations among Azeri Turkish patients from northwestern Iran. METHODS: One hundred ninety unrelated patients were referred by specialists to the Molecular-Medical Genetic Center of Tabriz. A clinical diagnosis of FMF was made according to published criteria. Mutation screening of the MEFV gene was performed for the 5 most commonly known mutations, namely M694V, V726A, M680I, M694I, and E148Q, by using amplification refractory mutation system for the first 4 and by polymerase chain reaction restriction-digestion testing for E148Q. These methods may also be used as a screening tool within affected families. RESULTS: Of the unrelated patients investigated, 120 (63%) had 1 or 2 mutations. Of those with mutations, 41 were homozygous, 37 were compound heterozygous, and 42 had only 1 identifiable mutation. Of the studied alleles, the most frequent mutation was M694V (28%), followed by V726A (9%), E148Q (7%), M680I (7%), and M694I (1%) mutations. CONCLUSIONS: Our results indicate that the common Mediterranean mutations are frequent in the Azeri Turkish FMF patients but with some differences in the frequency of individual mutations. The high frequency of E148Q in Azeri Turks compared with Mediterranean ethnic groups is rather interesting. The results open the way for further investigations on patients diagnosed as having FMF and in whom no mutations or only 1 mutated allele were found.     

Mutations in the gene for familial Mediterranean fever: do they predispose to inflammation?

OBJECTIVE: To analyze 70 individuals who were found to have the Mediterranean fever (MEFV) gene for the presence of definite familial Mediterranean fever (FMF) and to assess if they were prone to clinical and laboratory inflammation. We also prospectively evaluated 72 patients with childhood rheumatic diseases for the presence of MEFV mutations. METHODS: Seventy patients with one MEFV gene mutation were reevaluated for the presence of a clinical FMF phenotype using a new set of criteria. They were also questioned for the presence of musculoskeletal symptoms and rheumatic diseases. They were sampled for erythrocyte sedimentation rates and C-reactive protein levels. A second group with childhood rheumatic diseases were diagnosed according to international criteria. RESULTS: Median age of the 70 heterozygous individuals was 12 years. About 1/3 (34.3%) were classified with clinical FMF phenotype according to the suggested criteria. Fifteen (21.4%) were classified as normal and 3 (4.3%) had recurrent abdominal pains but did not fulfill all criteria for clinical FMF. Overall, 28 (40.0%) had some form of rheumatic complaint and 15 (21.4%) had developed a rheumatic disease including Beh?et's disease, a vasculitis, or acute rheumatic fever. The mean ESR and CRP levels were 45.47 +/- 33.05 mm/h and 4.00 +/- 6.73 mg/dl, respectively. Among the 72 patients with rheumatic diseases of childhood, 22 (30.5%) carried one or 2 mutations of the MEFV gene. The mutated allele frequency among patients with rheumatic diseases was significantly higher than those in controls (p < 0.05). Within this group, among the 59 patients with juvenile idiopathic arthritis 15 had mutations in the heterozygous or homozygous form. CONCLUSION: We confirm the acute phase response in the carriers for MEFV mutations. We suggest that these patients may have a tendency to develop certain manifestations due to an increased baseline of inflammation, and the presence of these mutations may affect their disease course when they develop rheumatic disease.     

Clinical and diagnostic value of genetic testing in 216 Israeli children with Familial Mediterranean fever

OBJECTIVE: Familial Mediterranean fever (FMF) is an autosomal recessive disease with diverse clinical presentation. The FMF gene (MEFV) has recently been cloned and 30 point mutations causing the disease have been identified. We appraised the value of mutation analysis as a diagnostic test for FMF in symptomatic pediatric patients, and explored the possible correlations between MEFV genotypes and the diverse phenotypic expression of the disease. METHODS: Two hundred sixteen children who met the clinical criteria for FMF underwent molecular genetic studies to detect the 3 most common mutations in the Israeli FMF patient population (M694V, V726A, E148Q). The mutations found were related to clinical presentation and disease severity, using the Tel-Hashomer severity score. RESULTS: Of the 216 children who fulfilled the diagnostic criteria for FMF, 82 (38.0%) had 2 of the tested mutations, 73 (33.8%) had only one mutation, and 61 (28.2%) had none of the mutations studied. The M694V was the most frequent mutation, detected in 174 of 432 MEFV alleles (40.0%). The V726A mutation was found in 39 alleles (9.0%) and the E148Q mutation in 25 (5.8%). The severity score correlated with the number of mutations. Children with no mutations presented at an older age compared to children with one or 2 mutations. Children homozygous for the M694V mutation presented at a younger age, had a higher severity score, and more commonly had arthritis. CONCLUSION: Limited genetic molecular testing for MEFV mutations may explain some of the FMF clinical variability, but is diagnostically ineffective. The use of clinical criteria remains essential in establishing the diagnosis of FMF.     

MEFV mutations in patients with familial Mediterranean fever in the Black Sea region of Turkey: Samsun experience [corrected

OBJECTIVE: To investigate MEFV mutations among patients with familial Mediterranean fever (FMF), their relatives, and healthy controls in the Black Sea region of Turkey; to compare 3 different MEFV mutation analysis methods; to evaluate the role of MEFV mutations in the diagnosis of FMF; and to investigate the role of M694V in the development of amyloidosis. METHODS: In total, 890 subjects (625 patients, 165 relatives, 100 healthy controls) were included in this prospective study. MEFV mutations were studied with the amplification refractory mutation system (ARMS; n = 335), polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP; n = 335), and reverse hybridization assay (FMF StripAssay; n = 693). RESULTS: All methods were used in 79 patients. The ratio of false negativity was about 2% using ARMS compared to PCR-RFLP. The FMF StripAssay was used to investigate 9 more mutations and detected 17 mutations in 14 patients. The M694V/M694V genotype was more common in patients with amyloidosis (37%) compared to patients without amyloidosis (18%) (p = 0.009). The frequency of MEFV carriers was 27%. The frequency of individuals having 2 mutations among asymptomatic relatives of FMF patients was 6%. CONCLUSION: The FMF StripAssay is a reliable and time-saving method. In spite of detection of new mutations and developments in MEFV assay technology, there were patients in whom no mutation was detected. Our data, combined with previous studies, show that patients having M694V/M694V carry a risk for amyloidosis.     

MEFV mutations in Moroccan patients suffering from familial Mediterranean Fever

Familial Mediterranean Fever (FMF, MIM 249100) is an autosomal recessive disease mainly affecting patients of the Mediterranean basin. It is an autoinflammatory periodic disorder characterised by recurrent episodes of fever and abdominal pain, synovitis and pleuritis. FMF is caused by mutations in the Mediterranean Fever (MEFV) gene located on chromosome 16p13.3. Several mutations in the MEFV gene have been characterised in different populations. However, very little is known about mutations in the MEFV gene in patients with Moroccan origin. The aim of this study is to determine the clinical components of FMF and characterise mutations in the MEFV gene in Moroccan patients. The study was carried out on 120 unrelated Moroccan patients referred to the department of medical genetics in Rabat for suspicious FMF over a period of 10 years. Patients were screened for the most common MEFV mutations by direct sequencing of exons 2 and 10. Of the 120 unrelated patients investigated, 56 patients (47%) were carriers of one or two MEFV mutations, and 64 patients (53%) had no detected mutations. Of those with mutations, 24 were homozygous (44%), 13 were compound heterozygotes (24%), and 19 patients had only 1 identifiable mutation (32%). The most frequent mutation in Moroccan patients is M694V (47%), followed by M694I (32%), A744S (6.5%), M680L (4%), M694del (2%) and E148Q (6.5%). The R761H, K695R and I692del mutations were rarely encountered (less than 1%). The V726A mutation was not found in our study. Our data represent the first report of MEFV gene mutations causing FMF in Moroccans patients. The M694V and M694I mutations are the most common mutations found in MEFV gene in Moroccan population; while the most common mutation in Arabs from the Middle-East region, the V726A, was not found in our population.     

Familial Mediterranean fever: high gene frequency and heterogeneous disease among an Israeli-Arab population

OBJECTIVE: Familial Mediterranean fever (FMF) is an autosomal recessive disease that primarily affects non-Ashkenazi Jews, Armenians, Arabs, and Turks. The FMF (MEFV) gene responsible for the disease has been recently identified. Four missense mutations in exon 10 of the FMF gene seem to account for 86% of the DNA variations identified in patients with FMF. We conducted a phenotype/genotype correlation study in a homogenous population of Israeli-Moslem Arab patients with FMF and performed a mutational screening analysis on DNA samples from healthy individuals of this ethnic group. METHODS: Sixty-five patients clinically diagnosed as having FMF underwent molecular genetic studies using polymerase chain reaction and restriction endonuclease digestion methods to detect the presence of the 4 mutations (M694V, V726A, M680I, M694I). We then correlated the presence of each mutation with age of onset, clinical manifestations, and disease severity; patients whose allelic combination included M694V were then excluded from further statistical analysis, since the association of severe disease with the M694V allele has already been shown. In addition, we screened for FMF mutations the DNA samples from 318 healthy Moslem Arab individuals for the presence of these mutations. RESULTS: Among the 65 patients who were clinically diagnosed as having FMF, 78.5% had one or 2 mutation-bearing chromosomes. The most prevalent mutation was V726A, followed by M680I, M694V, and M6941. No significant difference in phenotypic characteristics was found between the patients with the diverse mutations. The total carrier frequency for the 4 mutations was 10.4% (95% confidence interval 0.07 to 0.137). CONCLUSION: A high FMF gene frequency was found among an Israeli-Moslem Arab population. Among the FMF patients from this ethnic group, several mutations were detected, none of which was found to correlate with a severe course of the disease.