Pyrin/marenostrin mutations in familial Mediterranean fever

Evaluation of the Inflammatory Response After Eradication of Helicobacter pylori in Patients With Familial Mediterranean Fever

PURPOSE

Evaluation of the inflammatory response after Helicobacter pylori (Hp) eradication in patients with Familial Mediterranean Fever (FMF) during the non-attack period and determining whether there is a change in the ongoing inflammation during the non-attack period.

MATERIALS AND METHODS

Sixty-four patients, who have not been eradicated for Hp in the last 2 years, diagnosed with FMF, and evaluated in the non-attack period, were included in the study. Hp eradication therapy was administered to patients who were found to be Hp-positive. C-reactive protein (CRP), high-sensitive C-reactive protein (hs-CRP), interleukin-6, interleukin-8, tumor necrosis factor-alpha, and serum amyloid A values were compared between the groups before and after eradication.

RESULTS

CRP and hs-CRP levels were found to be statistically higher in the FMF group than in the control group. A statistically significant decrease was found in the values of CRP and hs-CRP, in the number of patients with attacks, and in attack frequency after eradication in the Infected Patients compared to the values before eradication.

CONCLUSIONS

We determined a decrease in CRP and hs-CRP values, the number of patients with attacks, and attack frequency with the eradication of Infected Patients. In patients with FMF, in whom it has been proven by different studies that the inflammation continues during the non-attack period, it may be recommended to investigate the presence of Hp infection, which is thought to contribute to this inflammation and to give Hp eradication therapy to patients who are found positive to reduce the development of secondary complications caused by chronic inflammation.

Investigation of the relationship between disease severity and development of amyloidosis and genetic mutation in FMF disease

BACKGROUND

Familial Mediterranean fever (FMF) is an autosomal recessive genetic disease. Amyloidosis is the most important complication of FMF that determines the prognosis of the disease.

AIMS

In our study, we have investigated the relationship between the genetic mutations with the disease severity and the frequency of development of amyloidosis inpatients with FMF.

METHODS

A total of 148 patients with FMF were included this study. The relationship between disease activity score, clinical findings, response to treatment, and presence of amyloid and genetic mutations were evaluated.

RESULTS

One hundred forty-eight patients (80 women (54%), 68 men (46%)) were enrolled over 18 years of age. The mean age of the patients was 30.98 ± 11.18 (18-67) years. In our study, the most frequently seen mutations are M694V, M680I, R202Q, and E148Q, respectively. The most common genotype is M694V/M694V mutation and this mutation has been found in 37 patients (25%). In 25 patients, M694V heterozygous have been found (16.8%). The third frequent mutationis M694V/M680I/R202Q has been found in13 patients (8.7%). In 23 patients, amyloidosis has been developed. Ten patients with amyloidosis have M694V homozygous mutations (27%) and 5 patients with amyloidosis M694V heterozygous (20%) mutations. The both of the two patients who carry the homozygous E148Q mutations have developed amyloidosis.

CONCLUSIONS

In our study, the distribution of the frequency of mutations is consistent with other similar studies performed in Turkey. We found that patients with M694V mutation had a significantly higher rate of exacerbation, higher drug doses for treatment, and a close relationship with amyloidosis, as compared to patients with other mutations.

[Familial Mediterranean fever in 2020]

Familial Mediterranean fever is the most frequent autoinflammatory disease with autosomal recessive transmission. Most patients carry mutations in the MEFV gene encoding the protein marenostrin/pyrin. It is characterised by short ant recurrent attacks of fever and serositis with abdominal or thoracic pain, usually lasting less than 3 days, raised inflammatory biologic markers in an individual of Mediterranean origin. Colchicine has been shown to be effective in prevention of inflammatory attacks and development of amyloidosis which is responsible of nephrotic syndrome and chronic renal failure. Better knowledge in pathogenic mechanisms permitted identification of interleukin-1 beta (Il-1 β) as the main cytokine target. Anti-IL-1 therapy must be considered as a second line treatment in case of persistent inflammation or colchicine intolerance.

Familial Mediterranean Fever: Assessing the Overall Clinical Impact and Formulating Treatment Plans

Recurrent self-limited attacks of fever and short-lived inflammation in the serosal membranes, joints, and skin are the leading features of familial Mediterranean fever (FMF), the most common autoinflammatory disorder in the world, transmitted as autosomal recessive trait caused by MEFV gene mutations. Their consequence is an abnormal function of pyrin, a natural repressor of inflammation, apoptosis, and release of cytokines. FMF-related mutant pyrins are hypophosphorylated following RhoA GTPases’ impaired activity and show a propensity to relapsing uncontrolled systemic inflammation with inappropriate response to inflammatory stimuli and leukocyte spread to serosal membranes, joints or skin. Typical FMF phenotype 1 consists of brief episodes of inflammation and serositis, synovitis, and/or erysipelas-like eruption, whereas phenotype 2 is defined by reactive amyloid-associated (AA) amyloidosis, which is the most ominous complication of FMF, in otherwise asymptomatic individuals.

Furthermore, FMF phenotype 3 is referred to the presence of two MEFV mutations with neither clinical signs of FMF nor AA amyloidosis. The influence of epigenetic and/or environmental factors can contribute to the variable penetrance and phenotypic heterogeneity of FMF. Colchicine, a tricyclic alkaloid with anti-microtubule and anti-inflammatory properties, is the bedrock of FMF management: daily administration of colchicine prevents the recurrence of FMF attacks and the development of secondary AA amyloidosis. Many recent studies have also shown that anti-interleukin-1 treatment is the best therapeutic option for FMF patients nonresponsive or intolerant to colchicine. This review aims to catch readers’ attention to the clinical diversity of phenotypes, differential diagnosis, and management of patients with FMF.

SEROLOGICAL SCREENING FOR CELIAC DISEASE IN CHILDREN WITH COLCHICINE-RESISTANT FAMILIAL MEDITERRANEAN FEVER

BACKGROUND

Familial Mediterranean fever and celiac disease share some common clinical features such as abdominal pain, diarrhea, arthralgia and arthritis. Also, both of the diseases are associated with many inflammatory and autoimmune diseases. Previous studies have shown the association between familial Mediterranean fever (FMF) and different clinical conditions.

OBJECTIVE

We aimed to investigate the relationship between celiac disease and colchicine-resistant familial Mediterranean fever (crFMF) disease.

METHODS

This prospective study was conducted at the Department of Pediatric Gastroenterology and Pediatric Rheumatology from October 2015 to August 2016. A total of 24 patients with crFMF were included in the study. We used 60 sex- and age-matched healthy subjects as a control group. Levels of total IgA and tissue transglutaminase (tTG) IgA antibody were measured in both groups. Those with increased level of tTG IgA were tested for anti-endomysium IgA antibodies (EMA). Gastroduodenoscopy and intestinal biopsy were planned for a definite diagnosis of celiac disease in patients with positive EMA.

RESULTS

Of the 24 patients in this study, 18 (75.0%) were female. Only 4 (16.6%) of 24 patients were positive for tTG IgA. Patients with positive tTG IgA were then tested for EMA IgA antibodies and none of them had a positive result. Only one (1.6%) subject from the control group was positive for tTG IgA but EMA positivity was not detected.

CONCLUSION

We did not found celiac disease in 24 children with crFMF. Since crFMF disease is rarely seen in general population, further studies with more patients are needed to provide more precise interpretation.

Comprehensive analysis of mutations in the MEFV gene reveal that the location and not the substitution type determines symptom severity in FMF

Background

Familial Mediterranean Fever (FMF) is an autoinflammatory disorder caused by mutations in the MEFV gene. These mutations appear in different populations with different frequencies and their caused symptom severities vary from mild to moderate to severe depending on the mutation type.

Methods

In this study, we analyzed the mutations that have been reported in the MEFV gene from symptomatic FMF patients and compared their frequencies in different populations from the 1000 Genome and the Exome databases, using statistical clustering. We also analyzed the nucleotide and amino acid substitution patterns across the MEFV gene.

Results

We found 16 (8%) nonsynonymous mutations outside exon 10 that did not cluster with known disease‐causing mutations (DCMs), due to their high frequencies in other populations. We also studied the substitution patterns for nucleotides and amino acids to determine the conserved and variable regions in the MEFV gene. In general more nonsynonymous substitutions were reported in exons 2, 3, and 10 from the FMF database (symptomatic FMF patients) compared to the 1000 Genome and the Exome databases. The same was true for amino acid (AA) substitutions where there were 1.5 times more radical (RAD) to conservative (CON) changes. However, when it came to AA substitutions exon 10 was quite conserved with a RAD/CON ratio of 0.9. In fact, we report that the most severe FMF symptoms are caused by conservative mutations in two highly conserved exon 10 regions.

Conclusion

We found presumptive FMF‐causing mutations that did not cluster with DCMs based on their allele frequencies. We also observed that the type of mutation is less likely to determine the severity of the FMF symptoms; rather it was the location of the mutations that was the determining factor.

Coexistence of sarcoidosis and Familial Mediterranean Fever

Sarcoidosis is a chronic inflammatory disease with unknown cause characterized by non-caseating granuloma formations. It may present with bilateral hilar lymphadenopathy, skin lesions, the involvement of eye and symptoms on the locomotor system. FMF (Familial Mediterranean Fever) is an autosomal recessive autoinflammatory disease, characterized by recurrent episodes of fever and polyserositis. Simultaneous occurrence of these diseases is rare. In this paper, we reported the coexistence of sarcoidosis with FMF.

The frequency of the celiac disease among children with familial Mediterranean fever

We aimed to assess the frequency of celiac disease (CD) in patients with Familial Mediterranean Fever (FMF). This prospective study was carried out from October 2015 to March 2016 and included 303 patients with FMF. We used 98 sex- and age-matched healthy subjects as a control group. Levels of total IgA and tissue transglutaminase (tTG) IgA antibody were measured in all groups. Those with increased level of tTG IgA were tested for anti-endomysium IgA antibodies (EMA). Patients with positive EMA underwent gastro-duodenoscopy and intestinal biopsy for a definite diagnosis of CD. Only 9 of 303 patients (2.9%) were positive for tTG IgA. Patients positive for tTG IgA were then tested for EMA and only one of them (0.3%) had a positive result. This patient underwent gastro-duodenoscopy. The pathological report was compatible with Marsh 0 classification score for the diagnosis of CD. Two subjects from the control group were positive for tTG IgA but none of them had positive EMA antibodies. We did not find CD in the large cohort of childhood FMF patients. The prevalence of CD did not show association with presence of childhood FMF in this study and CD would not be a considerable complication of childhood FMF.

A novel insertion mutation identified in exon 10 of the MEFV gene associated with Familial Mediterranean Fever

Background

Familial Mediterranean Fever (FMF), characterized by recurrent fever and inflammation of serous membranes, is an autosomal recessive disease caused by mutations in the Mediterranean fever (MEFV) gene. Around 296 mutations have been reported to date.

Methods

Two two-generation Turkish families with a total of four members diagnosed with FMF clinically were screened with DNA sequencing performed on exon 2 and exon 10 of the MEFV genes. Then, complete exome sequencing analysis of MEFV gene was done for four patients in whom novel mutation was detected.

Results

A novel single base Guanine (G) insertion mutation in the coding region of MEFV gene, named c.2330dupG (p.Gln778Serfs*4 or Q778SfsX4) resulting in a mutated Pyrin/Marenostrin protein was identified.

Conclusions

This is the first report of a new mutation in exon 10 of the MEFV gene in two Turkish families. This novel pattern of insertion mutation may provide important information for further studies on FMF pathogenesis.

A case of familial Mediterranean fever associated with compound heterozygosity for the pyrin variant L110P-E148Q/M680I in Japan

Familial Mediterranean fever (FMF) is an autosomal recessive disorder characterized by recurrent and self-limited fever attacks and serositis/arthritis. The M694V, M694I, M680I, V726A, and E148Q mutations in MEFV, the gene responsible for FMF, account for most FMF cases in Mediterranean populations. In Japan, M694I and E148Q are most frequently detected; M694V, M680I, and V726A have not been identified so far. We report the first case of FMF associated with M680I in Japan.

The crystal structure of human pyrin b30.2 domain: implications for mutations associated with familial Mediterranean fever

The inherited autoinflammatory syndrome familial Mediterranean fever (FMF) is characterized by recurrent episodes of fever, which are independent of any bacterial or viral infections. This disease is associated with point mutations in the mefv gene product pyrin. Although the precise molecular functions of pyrin are unknown, it seems to be involved in the maturation and secretion of interleukin-1beta. Approximately two thirds of all FMF-associated mutations cluster in the C-terminal B30.2 domain of pyrin. To investigate the molecular consequences of FMF-associated mutations, we determined the crystal structure of the pyrin B30.2 domain at 1.35-A resolution. The comparison with other B30.2/ligand complex structures revealed a shallow cavity, which seems to be involved in binding the pyrin ligand. The bottom of this cavity is covered mainly with hydrophobic amino acids, suggesting that pyrin recognizes its ligand by hydrophobic contacts and surface complementarities. FMF-associated mutations cluster around two sites on the B30.2 surface. Approximately two thirds, including those mutations with the most severe disease outcomes, are observed in the vicinity of the predicted peptide binding site, suggesting that they will have a direct impact on ligand binding. A second mutational hot spot was observed on the opposite side of the B30.2 domain in the neighbourhood of its artificial N-terminus. Although most FMF-associated mutations are solvent exposed, several will modify the main-chain conformation of loops. The experimental crystal structure of the pyrin B30.2 domain serves as a basis for an accurate modelling of these mutations.

Gastric changes following colchicine therapy in patients with FMF

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Familial Mediterranean Fever in Lebanon: founder effects for different MEFV mutations

Haplotype analysis of 376 Familial Mediterranean Fever (FMF) patients and 100 controls from Lebanon was performed using 4 microsatellite loci to study founder effects for the five most frequent mutations within the MEFV gene (M694V, M694I, V726A, M680I and E148Q). Each of these mutations was associated with a particular haplotype that was less frequent among controls, confirming that they have probably arisen from unique mutation events and that the carrier chromosomes derived from a common ancestor. The estimated ages of the most recent common ancestor for each of the 5 mutations, using the ESTIAGE program, were 7000, 8500, 15000, 23000 and 30000 years for M694V, M694I, V726A, M680I and E148Q, respectively. Varying the mutation rate at one of the markers led to younger age estimates, but the mutation E148Q remained the oldest one. Comparison of haplotype distributions among the different Lebanese religious groups confirmed that Muslim sub-populations (Shiites and Sunnites) as well as Christian ones, including Armenians who were formerly settled in the South-Eastern part of Asia Minor (Cilicia), are all derived from an ancient common ancestral population in which most of the MEFV mutations were already present with their respective associated haplotypes.

MEFV gene mutations spectrum among Lebanese patients referred for Familial Mediterranean Fever work-up: Experience of a major tertiary care center

Familial Mediterranean Fever (FMF) is an autosomal recessive inflammatory disorder predominantly affecting people living in or originating from areas around the Mediterranean Sea, mainly Jews, Armenians, Turks, and Arabs. It is characterized by recurrent attacks of inflammation of serosal membranes and fever resulting in acute abdominal, chest, or joint pain. Over 50 MEditerranean FeVer (MEFV) mutations and polymorphisms have been identified in FMF patients. The objective of this study was to analyze the distribution and frequencies of 12 MEFV mutations in 266 referred Lebanese patients using a reverse-hybridization assay. Of the 266 patients, 129 (48.5%) were positive for at least one mutation and 137 (51.5%) had no mutations detected. Of the 129 patients with mutations, 35 were homozygous, 41 were compound heterozygous and 53 were heterozygous. The five most common mutations M694V, E148Q, V726A, M694I and M680I (G/C) accounted for 26.1, 22.2, 21.3, 9.6 and 7.7%, respectively. The A744S, F479L, R761H and I692del were encountered in 2.9% of patients; P369S and M680I (G/A) were found in 1.2% of patients while K695R was absent. The spectrum of the MEFV mutations among our sampled Lebanese FMF patients shows the high heterogeneity at the allelic level when compared to Arab and non-Arab populations. The most important feature was the relatively high frequency of the E148Q in our study group that allows us to question it as a mutation rather than a polymorphism. Further studies should be conducted to evaluate the role of the E148Q allele.

Population genetics of familial Mediterranean fever: a review

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

Pyrin-only protein 2 modulates NF-kappaB and disrupts ASC:CLR interactions

NF-kappaB is pivotal for transactivation of cell-cycle regulatory, cytokine, and adhesion molecule genes and is dysregulated in many cancers, neurodegenerative disorders, and inflammatory diseases. Proteins with pyrin and/or caspase recruitment domains have roles in apoptosis, innate immunity, and inflammation. Many pyrin domain (PYD) proteins modulate NF-kappaB activity as well as participate in assembling both the perinuclear "apoptotic speck" and the pro-IL1beta/IL-18-converting inflammasome complex. "Pyrin-only" proteins (POP) are attractive as negative regulators of PYD-mediated functions and one such protein, POP1, has been reported. We report the identification and initial characterization of a second POP. POP2 is a 294 nt single exon gene located on human chromosome 3 encoding a 97-aa protein with sequence and predicted structural similarity to other PYDs. Highly similar to PYDs in CATERPILLER (CLR, NLR, NALP) family proteins, POP2 is less like the prototypic pyrin and ASC PYDs. POP2 is expressed principally in peripheral blood leukocytes and displays both cytoplasmic and nuclear expression patterns in transfected cells. TNF-alpha-stimulated and p65 (RelA)-induced NF-kappaB-dependent gene transcription is inhibited by POP2 in vitro by a mechanism involving changes in NF-kappaB nuclear import or distribution. While colocalizing with ASC in perinuclear specks, POP2 also inhibits the formation of specks by the CLR protein CIAS1/NALP3. Together, these observations demonstrate that POP2 is a negative regulator of NF-kappaB activity that may influence the assembly of PYD-dependent complexes.

The value of the levels of acute phase reactants for the prediction of familial Mediterranean fever associated amyloidosis: a case control study

In order to determine the role of levels of acute phase proteins (APPs) for the development of amyloidosis in familial Mediterranean fever (FMF) patients, the levels of serum amyloid A (SAA), C reactive protein (CRP), fibrinogen and erythrocyte sedimentation rate were measured in paired sera of 36 FMF patients during and in between acute attacks, 39 of their healthy parents (obligate heterozgotes), and 15 patients with FMF associated amyloidosis. To compare the levels of APPs, 39 patients with chronic infections or inflammatory diseases who may develop secondary amyloidosis, 20 patients with acute infections who are known to have elevated acute phase response but will never develop amyloidosis and 19 healthy controls were included. The median levels of all APPs are increased in the patients with FMF during attacks and a significant decrease was observed after the attack was over. The level of SAA was above reference range in all FMF patients during the attack free period and the level of at least one other APP was also above normal in 64% of the patients. Both CRP and SAA levels were found to be higher in obligate heterozygotes compared to controls. The levels of SAA in patients with FMF during the attack-free period, obligate heterozygotes and patients with FMF-amyloidosis were found to be similar. The levels in each group were found to be higher than SAA levels found in healthy controls yet lower than the levels measured in the patients with acute infections and patients with chronic inflammation or chronic infections. In conclusion, our results show that SAA level reflects subclinical inflammation with high sensitivity but its value for the prediction of amyloid formation process seems to be low.

The contribution of genotypes at the MICA gene triplet repeat polymorphisms and MEFV mutations to amyloidosis and course of the disease in the patients with familial Mediterranean fever

OBJECTIVE

To evaluate the effects of MEFV genotypes and the major histocompatibility complex class I chain-related gene A (MICA) triplet repeat polymorphism on the severity and clinical features of familial Mediterranean fever (FMF) and amyloidosis in a group of Turkish FMF patients.

METHODS

We evaluated 105 adult FMF patients (with or without amyloidosis, 33 and 72, respectively) along with 107 healthy controls who were neither related to the patients nor had a family history of FMF or Behcet's disease. After recording the demographic and clinical data, the predominant mutations in the MEFV gene locus (M694V, M680I, V726A, M694I, and E148Q) were investigated by direct sequencing. MICA transmembrane polymorphisms in exon 5 were studied by vertical gel electrophoresis and fragment analysis of the amplicons obtained from MICA locus with appropriate primers.

RESULTS

Earlier age at onset, increased frequency of attacks, arthritis attacks, erysipelas-like erythema, increased severity scores and amyloidosis were significantly more common in M694V homozygous patients compared to the patients not M694V homozygous (P = 0.005, OR 4.55; P = 0.001, OR 7.60; P = 0.003, OR 4.57; P = 0.002, OR 7.58; P = 0.004, OR 5.15 and P = 0.018, OR 3.33, respectively). We did not detect any modifying effects of MICA alleles as an independently risk factor on the amyloidosis development. However, when we examined the effects of MICA alleles on the course of the disease and development of amyloidosis in the M694V homozygous patients, A5 allele had a protective effect against the development of amyloidosis (P = 0.038, OR(adj) 0.26 with A5 and P = 0.009, OR(adj) 4.42 without A5).

CONCLUSION

Though the effects of the MEFV genotypes seem clear, there are definitely other modifying factors or genes on the development of amyloidosis and on the course of the disease. For example, some MICA alleles have a protective effect on the prognostic factors in FMF.

Mutational analysis of the PRYSPRY domain of pyrin and implications for familial mediterranean fever (FMF)

Familial Mediterranean fever (FMF) is an autosomal, recessively inherited disease, characterized by recurrent fever and serositis that affects mainly patients of the Mediterranean basin. The gene responsible for FMF, named MEFV, was cloned and several missense mutations were found to be responsible for the disease. Based on a recent molecular analysis of MEFV gene mutations in 43 patients from Crete aiming to correlate specific genotypes and clinical manifestations of FMF, we were prompted to construct a three-dimensional model (3-D model) of the PRYSPRY domain of pyrin. The majority of the known MEFV mutations located on this domain have been classified, according to disease severity, and localized on this 3-D model. The functional consequences of these mutations and their implications on disease severity are discussed. Moreover, we report a putative novel missense mutation, S702C, which we identified in exon 10 of the MEFV gene and localized on the constructed 3-D model.

Familial mediterranean fever in Arabs

Autoinflammatory diseases are a group of disorders characterised by seemingly unprovoked inflammation in the absence of high-titre autoantibodies or antigen-specific T cells, and include the hereditary periodic fever syndromes. Familial Mediterranean fever (FMF) is an archetypal autoinflammatory disorder, which is autosomal recessive and has a high prevalence in non-Ashkenazi Jews, Armenians, Turks, and Arabs. The classic clinical picture is recurrent acute short-lived febrile and painful attacks with variable periods of remission. In a subset of patients, the disorder is complicated by amyloidosis that leads to renal failure. The gene responsible for FMF--MEFV--has been identified and its role in inflammation is being assessed. There seems to be a distinctive clinical picture in Arab patients with FMF, and the range and distribution of MEFV mutations is different from that noted in other affected ethnic groups. Here, we discuss the clinical and molecular aspects of FMF in Arabs.

Familial Mediterranean fever in a childhood population in eastern Turkey

BACKGROUND

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of inflammation of serosal membranes. Amyloidosis is the most severe complication of the disease The aim of this study was to explore the magnitude of the FMF problem and to describe clinical phenotypic and genotypic profile in the childhood population in Eastern Turkey.

METHODS

In this study, 52 patients who were diagnosed as FMF between January 2000 and January 2003 in Department of Pediatrics, Ataturk University Hospital, were included. The diagnosis of FMF was based on typical clinical and laboratory features. The 12 FMF mutations were investigated in the patients.

RESULTS

Of the 52 patients, 30 (57.7%) were girls, 22 (42.3%) were boys, and the age ranged from 9 months to 15 years (8.5 +/- 3.2 years). A positive family history for FMF was noted in 33 (63.5%) patients. The mean onset age was 6 +/- 3.4 (from 8 months to 14 years). Nineteen children (36.5%) were symptomatic below the age of 5 years. Abdominal pain was observed in 50 (96.2%), fever in 42 (80.8%), arthralgia in 29 (55.8%), arthritis in 18 (34.6%), splenomegaly in 11 (21.2), hepatomegaly in 15 (28.8%), myalgia in 11 (26.2%), erysipelas-like erythema in 10 (19.2%), thoracic pain in four (7.7%), protracted febrile myalgia in three (5.8%), and seizures in two (3.8%). The most frequent mutation was the M694V/M694V. Clinical presentation of the patients was not different in respect with genotypes (P > 0.05). Two patients had chronic renal disease suggestive of amyloidosis.

CONCLUSION

It was noted that the FMF patients in this study had a broad spectrum of mutation combination, which might reflect the intercultural interactions of ancient ethnic groups that lived in Anatolia, and these mutations were not significantly different in respect to clinical presentations.

Familial Mediterranean fever

Familial Mediterranean fever (FMF) is the most frequent hereditary inflammatory disease characterized by self-limited recurrent attacks of fever and serositis. It is transmitted in an autosomal recessive pattern and affects certain ethnic groups mainly Jews, Turks, Arabs, and Armenians. FMF is caused by mutations in MEFV gene, which encodes pyrin. This protein is expressed mainly in myeloid/monocytic cells and modulates IL-1beta processing, NF-kappaB activation, and apoptosis. A mutated pyrin probably results in uncontrolled inflammation. The most devastating complication of FMF is amyloidosis, leading to chronic renal failure. M694V homozygocity, male gender and the alpha/alpha genotype of serum amyloid A1 gene are the currently established risk factors for development of amyloidosis. Daily colchicine is the mainstay of the therapy for the disease, resulting in complete remission or marked reduction in the frequency and duration of attacks in most patients. It is also effective in preventing and arresting renal amyloidosis.

Familial Mediterranean fever

Familial Mediterranean fever (FMF) is the most frequent hereditary inflammatory disease characterized by self-limited recurrent attacks of fever and serositis. It is transmitted in an autosomal recessive pattern and affects certain ethnic groups mainly Jews, Turks, Arabs, and Armenians. FMF is caused by mutations in MEFV gene, which encodes pyrin. This protein is expressed mainly in myeloid/monocytic cells and modulates IL-1beta processing, NF-kappaB activation, and apoptosis. A mutated pyrin probably results in uncontrolled inflammation. The most devastating complication of FMF is amyloidosis, leading to chronic renal failure. M694V homozygocity, male gender and the alpha/alpha genotype of serum amyloid A1 gene are the currently established risk factors for development of amyloidosis. Daily colchicine is the mainstay of the therapy for the disease, resulting in complete remission or marked reduction in the frequency and duration of attacks in most patients. It is also effective in preventing and arresting renal amyloidosis.

The Spectrum of Familial Mediterranean Fever Gene Mutations in Arabs: Report of a Large Series

OBJECTIVES

To identify the frequency and distribution of familial Mediterranean fever (FMF) gene (MEFV) mutations in Arab patients.

PATIENTS AND METHODS

The study was performed in the pediatric FMF clinic of Jordan University Hospital over a period of 4 years. Patients were referred by their physicians for diagnosis, management, genetic study, and counseling. A diagnosis of FMF was made according to published criteria. Screening for 5 mutations, namely M694V, V726A, M694I, M680I, and E148Q, was performed by amplification refractory mutation system (ARMS) for the first 4 and by restriction endonuclease testing for E148Q.

RESULTS

Of the 407 unrelated patients investigated, 239 (59%) had 1 or 2 mutations and 168 (41%) had none of the studied mutations detected. Of those with mutations, 92 were homozygous, 53 were compound heterozygotes, 3 had complex alleles, and 91 patients had only 1 identifiable mutation. Of the mutations, M694V, V726A, M694I, M680I, and E148Q accounted for 38, 26, 14, 10 and 13%, respectively. Twelve of our patients developed the protracted febrile myalgia syndrome (PFMS) of whom 5 (42%) were homozygous for M694V. Only 2 developed chronic renal failure, both of whom were homozygous for M694V and were not on colchicine prophylaxis. However, 43 patients had a family history of chronic renal failure, and 15 (35%) were homozygous for M694V.

CONCLUSIONS

Our data indicate that the 5 MEFV mutations are well distributed in Arabs. They also show that M694V is the most common mutation in Arab patients with FMF and seems to have an association with the development of amyloidosis and the PFMS. The high frequency of V726A, and the unique high frequency of M694I in Arabs compared with 3 other ethnic groups, are confirmed.

Acute renal insufficiency after high-dose melphalan in patients with primary systemic amyloidosis during stem cell transplantation

BACKGROUND

Patients with primary systemic amyloidosis (AL) have a poor prognosis. Median survival time from standard treatments is only 17 months. High-dose intravenous melphalan followed by peripheral blood stem cell transplant (PBSCT) appears to be the most promising therapy, but treatment mortality can be high. The authors have noted the development of acute renal insufficiency immediately after melphalan conditioning. This study was undertaken to further examine its risk factors and impact on posttransplant mortality.

METHODS

Consecutive AL patients who underwent PBSCT were studied retrospectively. Acute renal insufficiency (ARI) after high-dose melphalan was defined by a minimum increase of 0.5 mg/dL (44 micromol/L) in the serum creatinine level that is greater than 50% of baseline immediately after conditioning. Urine sediment score was the sum of the individual types of sediment identified on urine microscopy.

RESULTS

Of the 80 patients studied, ARI developed in 18.8% of the patients after high-dose melphalan. Univariate analysis identified age, hypoalbuminemia, heavy proteinuria, diuretic use, and urine sediment score (>3) as risk factors. Age and urine sediment score remained independently significant risk factors in the multivariate analysis. Patients who had ARI after high-dose melphalan underwent dialysis more often (P = 0.007), and had a worse 1-year survival (P = 0.03).

CONCLUSION

The timing of renal injury strongly suggests melphalan as the causative agent. Ongoing tubular injury may be a prerequisite for renal injury by melphalan as evidenced by the active urinary sediment. Development of ARI adversely affected the outcome after PBSCT. Effective preventive measures may help decrease the treatment mortality of PBSCT in AL patients.

Familial Mediterranean fever (FMF) in Turkey: results of a nationwide multicenter study

Familial Mediterranean fever (FMF) is an autosomal recessive disease that is prevalent among eastern Mediterranean populations, mainly non-Ashkenazi Jews, Armenians, Turks, and Arabs. Since a large proportion of all the FMF patients in the world live in Turkey, the Turkish FMF Study Group (FMF-TR) was founded to develop a patient registry database and analyze demographic, clinical, and genetic features. The cohort was composed of 2838 patients (mean age, 23.0 +/- 13.33 yr; range, 2-87 yr), with a male:female ratio of 1.2:1. There was a mean period of 6.9 +/- 7.65 years from disease onset to diagnosis; the period was about 2 years shorter for each decade since 1981. Ninety-four percent of patients were living in the central-western parts of the country; however, their familial origins (70% from the central-eastern and Black Sea regions) reflected not only the ongoing east to west migration, but also the historical roots of FMF in Turkey. Patients' clinical features included peritonitis (93.7%), fever (92.5%), arthritis (47.4%), pleuritis (31.2%), myalgia (39.6%), and erysipelas-like erythema (20.9%). Arthritis, arthralgia, myalgia, and erysipelas-like erythema were significantly more frequent (p < 0.001) among patients with disease onset before the age of 18 years. Genetic analysis of 1090 patients revealed that M694V was the most frequent mutation (51.4%), followed by M680I (14.4%) and V726A (8.6%). Patients with the M694V/M694V genotype were found to have an earlier age of onset and higher frequencies of arthritis and arthralgia compared with the other groups (both p < 0.001). In contrast to other reported studies, there was no correlation between amyloidosis and M694V homozygosity in this cohort. However, amyloidosis was still remarkably frequent in our patients (12.9%), and it was prevalent (27.8%) even among the 18 patients with a disease onset after age 40 years. Twenty-two patients (0.8%) had nonamyloid glomerular diseases. The high prevalence of vasculitides (0.9% for polyarteritis nodosa and 2.7% for Henoch-Schonlein purpura) and high frequency of pericarditis (1.4%) were striking findings in the cohort. Phenotype II cases (those patients with amyloidosis as the presenting or only manifestation of disease) were rare (0.3% or less). There was a high rate of a past diagnosis of acute rheumatic fever, which suggested a possible misdiagnosis in children with FMF presenting with recurrent arthritis. To our knowledge, this is the largest series of patients with FMF reported from 1 country. We describe the features of the disease in the Turkish population and show that amyloidosis is still a substantial problem.

Prevalence and significance of mutations in the familial Mediterranean fever gene in patients with Crohn's disease

The concurrence of Crohn's disease (CD) and familial Mediterranean fever was repeatedly reported. In this study we determined the distribution and contribution of MEFV gene mutations to CD susceptibility and clinical heterogeneity. An Israeli cohort of 209 CD patients (120 men and 89 women) was investigated for mutations in the MEFV gene. A detailed chart review, interview and physical examination were used to determine sociodemographic and clinical characteristics. MEFV and NOD2/CARD15 genotypes were analyzed in all patients and a genotype-phenotype correlation analysis was undertaken. The results of this study do not implicate MEFV mutations as major modifiers in CD. However, the E148Q MEFV variant was associated with susceptibility to perianal disease. More specifically, 19% (9/47) of CD patients with perianal disease carried the E148Q mutation compared to 6.7% (11/162) of CD patients without perianal involvement (OR 3.26, 95% CI 1.2-8.8, P=0.02). Although, for all mutations taken together, the prevalence of MEFV gene mutations among CD patients and controls was similar, the hypothesis that E148Q mutation modulates the phenotypic expression of CD is corroborated by the results of this study and needs to be further evaluated.

Renal expression of the C3a receptor and functional responses of primary human proximal tubular epithelial cells

Although complement activation and deposition have been associated with a variety of glomerulopathies, the pathogenic mechanisms by which complement directly mediates renal injury remain to be fully elucidated. Renal parenchymal tissues express a limited repertoire of receptors that directly bind activated complement proteins. We report the renal expression of the receptor for the C3 cleavage product C3a, a member of the anaphylatoxin family. C3aR is highly expressed in normal human and murine kidney, as demonstrated by immunohistochemistry and in situ hybridization. Its distribution is limited to epithelial cells only, as glomerular endothelial and mesangial cells showed no evidence of C3aR expression. The C3aR is also expressed by primary renal proximal tubular epithelial cells in vitro as demonstrated by FACS, Western blot, and RT-PCR. In vitro C3aR is functional in terms of its capacity to bind 125I-labeled C3a and generate inositol triphosphate. Finally, using microarray analysis, four novel genes were identified and confirmed as transcriptionally regulated by C3aR activation in proximal tubular cells. These studies define a new pathway by which complement activation may directly modulate the renal response to immunologic injury.

A severe autosomal-dominant periodic inflammatory disorder with renal AA amyloidosis and colchicine resistance associated to the MEFV H478Y variant in a Spanish kindred: an unusual familial Mediterranean fever phenotype or another MEFV-associated periodic inflammatory disorder?

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurring short attacks of fever and serositis. Secondary AA amyloidosis is the worst complication of the disease and often determines the prognosis. The MEFV gene, on chromosome 16p13.3, is responsible for the disease and around 30 mutations have been reported to date. Colchicine is the standard FMF treatment today, and prevents both attacks and amyloid deposition in 95% of patients. Here we describe a three-generation Spanish kindred with five family members affected by a severe periodic inflammatory disorder associated with renal AA amyloidosis and colchicine unresponsiveness. Clinical diagnosis of definite FMF disease was made based on the Tel-Hashomer criteria set. Genetic analyses revealed that all subjects were heterozygous for the new H478Y MEFV variant, segregating with the disease. In addition, mutations in the TNFRSF1A and CIAS1/PYPAF1/NALP3 genes, related to the dominantly inherited autoinflammatory periodic syndromes, were ruled out. However, the dominant inheritance of the disease, the long fever episodes with a predominant joint involvement, and the resistance to colchicine in these patients raise the question of whether the periodic syndrome seen in this kindred is a true FMF disease with unusual manifestations or rather another MEFV-associated periodic syndrome. We conclude that the new H478Y MEFV mutation is the dominant pathological variant causing the inflammatory periodic syndrome in this kindred and that full-length analyses of the MEFV gene are needed to obtain an adequate diagnosis of patients with clinical suspicion of a hereditary periodic fever syndrome, especially those from non-ancestral populations.

Prevalence and significance of mutations in the familial Mediterranean fever gene in Henoch-Schönlein purpura

OBJECTIVES

Based on the fact that Henoch-Schönlein purpura (HSP) occurs in approximately 5% of persons with familial Mediterranean fever (FMF), we assessed the prevalence and significance of FMF gene mutations in children with one or more episodes of HSP.

STUDY DESIGN

Thirty-four boys and 18 girls treated for HSP at Rambam Medical Center were interviewed and asked to donate blood. Mean age at disease onset was 6.7+/-2. 4 years, and mean follow-up was 3.8+/-1.3 years. Six predominant mutations (M694V, M680I, M694I, V726A, K695R, E148Q) in the MEFV gene were studied.

RESULTS

Nine heterozygotes, three homozygotes and two compound heterozygotes, were identified. Altogether, five persons (10%) carried two mutated MEFV alleles, a number significantly exceeding that determined for the general Israeli population (1%-2%). Of these, three displayed genotypes associated with a mild form of disease (M694V/E148Q and V726A/V726A), and two had genotypes normally observed in disease-free persons (E148Q/K695R and E148Q/E148Q).

CONCLUSIONS

Occult FMF cases much more numerous than expected were identified among children presenting with HSP. Such children should be closely monitored for renal complications, and treatment with colchicine should be considered.

Homology modeling provides insights into the binding mode of the PAAD/DAPIN/pyrin domain, a fourth member of the CARD/DD/DED domain family

The PAAD/DAPIN/pyrin domain is the fourth member of the death domain superfamily, but unlike other members of this family, it is involved not only in apoptosis but also in innate immunity and several other processes. We have identified 40 PAAD domain-containing proteins by extensively searching the genomes of higher eukaryotes and viruses. Phylogenetic analyses suggest that there are five categories of PAAD domains that correlate with the domain architecture of the entire proteins. Homology models built on CARD and DD structures identified functionally important residues by studying conservation patterns on the surface of the models. Surface maps of each subfamily show different distributions of these residues, suggesting that domains from different subfamilies do not interact with each other, forming independent regulatory networks. Helix3 of PAAD is predicted to be critical for dimerization. Multiple alignment analysis and modeling suggest that it may be partly disordered, following a new paradigm for interaction proteins that are stabilized by protein-protein interactions.

Familial Mediterranean fever (FMF) mutations occur frequently in the Greek-Cypriot population of Cyprus

Familial Mediterranean Fever (FMF) is an autosomal recessive disease of high prevalence within Mediterranean countries and particularly common in four ethnic populations: Arabs, non-Ashkenazi Jews, Armenians, and Turks. The responsible gene MEFV has been assigned to chromosome 16p13.3. Our aim was to establish the frequencies of the most common mutations in Greek-Cypriots. We found that 1 in 25 is a carrier of one of three mutations. V726A, M694V, and F479L. In 68 Grek-Cypriot FMF chromosomes analyzed, we found V726A (25%), F479L (20.6%), M694V (17.6%), and others (36.8%). Mutation F479L, relatively common in this population, is very rare elsewhere. Our study indicates that FMF is not a rare condition in Cyprus and that, because of the significant morbidity associated with this disorder, which is often diagnosed only after unnecessary surgeries, a newborn screening program to detect affected in this population may be warranted.

Reduced MEFV messenger RNA expression in patients with familial Mediterranean fever

OBJECTIVE

Familial Mediterranean fever (FMF) is the most common inherited periodic syndrome. The disease phenotype and the almost exclusive expression of the causative gene, MEFV, in leukocytes suggest that this gene plays an important role in the inflammatory cascade. Since most of the known mutations are conservative, we sought to determine how minor DNA defects can give rise to the dramatic phenotypic features seen in FMF.

METHODS

To address whether the molecular basis of the phenotype-genotype correlation could be related to altered MEFV messenger RNA (mRNA) expression, we quantified the relative abundance of MEFV transcripts in peripheral blood leukocytes from patients with FMF, healthy carriers of a single MEFV mutation, and healthy control subjects.

RESULTS

We found significantly lower expression of MEFV mRNA in genetically ascertained FMF patients than in healthy controls (0.7 versus 1.1; P = 0.00001). In healthy carriers, the mRNA levels were intermediate, suggesting a true dose-response relationship between the number of mutations and the abundance of MEFV transcripts. The difference between healthy controls and healthy carriers was significant (1.1 versus 0.8; P = 0.008), demonstrating that the decrease in mRNA expression is related to a molecular defect independent of FMF symptoms. MEFV mRNA expression was also found to be a function of the type of mutations. The lowest MEFV levels were found in healthy carriers and patients with M694V. Moreover, we observed an inverse correlation with the clinical severity score (r = -0.6, P = 0.04 and r = -0.6, P = 0.004 in patients with 1 and 2 M694V mutations, respectively).

CONCLUSION

Our results demonstrate that MEFV message levels are related to both the genotype and the phenotype, and suggest that the pathophysiology of FMF relies on a quantitative defect of MEFV mRNA expression.

Genotype/phenotype correlations in Arab patients with familial Mediterranean fever

OBJECTIVES

To study the phenotype/genotype correlations in Arab patients with familial Mediterranean fever (FMF).

PATIENTS AND METHODS

The study was performed in a 3-year period (February 1998-February 2001). Patients were seen in the pediatric FMF clinic of Jordan University Hospital, and the diagnosis of FMF was made according to published criteria. Screening for mutations was carried out by direct sequencing of the entire coding sequence of exon 10 and its donor splice site and by restriction endonuclease testing for mutations in exon 2. A total of 278 patients with clinically positive FMF were screened.

RESULTS

Of the 278 patients, 50 (18%) had 2 mutations identified, and 76 (27%) other patients had only 1 mutation identified. The 50 patients with 2 mutations are the subject of this report. The M694V/M694V and the M694V/V726A and M694I/M694I genotypes were the most common (30%, 16%, and 14%, respectively). Three homozygous genotypes (M694V/M694V, V726A/V726A, and M694I/M694I) and 2 compound heterozygous genotypes (M694V/V726A and V726A/M680I) accounted for 78% of mutations. The difference in the mean severity score (14 +/- 2) of the M694V/M694V group and the V726A/V726A (mean severity score, 10 +/- 3) and M694I/M6941 (mean severity score, 6 +/- 1) groups was statistically significant (P =.003 and.0, respectively). The difference between the M649V/M694V group and the M694V/V726A (mean severity score, 15 +/- 2) was not statistically significant (P = 0.31).

CONCLUSIONS

The genotypes M694V/M694V and M694V/V726A have a severe clinical course in Arab patients with FMF, whereas the M694I/M694I is associated with mild disease.

Thoracic and lung involvement in familial Mediterranean fever (FMF)

Lung involvement in FMF is limited mainly to transient pleuritis during acute attacks. Amyloidosis of the lung is rare and is associated with symptomatic involvement of other organs while remaining subclinical in itself. Vasculitis of the lung in FMF is possible because of the strong association between FMF and a variety of vasculitides. With the exception of one case of isolated pulmonary vasculitis, vasculitis of the lung in FMF has not been described. The claim that FMF protects against asthma has not been established, but this inverse association, if present, may be traced to linkage disequilibrium in which MEFV modifies the effect of asthma and atopic-related genes, or to eosinophil function. Mesothelioma has been reported in at least four patients with FMF and is related to chronic or recurrent stimulation of the serous membrane. Three patients had peritoneal mesothelioma, while one developed mesothelioma of the lung. Finally, thromboembolism should be considered, particularly in patients with FMF amyloidosis who present with respiratory distress.

Familial Mediterranean fever: the segregation of four different mutations in 13 individuals from one inbred family: genotype-phenotype correlation and intrafamilial variability

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurring attacks of fever and serositis. Six sequence alterations (M694V, V726A, K695R, M680I, M694I, and E148Q), in the MEFV gene, account for the majority of FMF chromosomes. Differences in the clinical expression have been mainly attributed to MEFV allelic heterogeneity. Homozygotes for the M694V mutation have a more severe form of the disease and more frequently demonstrate articular and renal complications. The clinical manifestations associated with mutation M680I are considered less severe. Mutations E148Q, K695R and V726A have reduced penetrance, and many individual homozygotes or compound heterozygotes for these mutations remain asymptomatic. Here we report on one inbred family with 13 individuals (one grandparent, three parents, and nine grandchildren), either homozygotes or compound heterozygotes, for one or two of four mutations (V726A, M694V, M680I, and K695R). Three parents and one grandparent who each carried two mutated alleles remained asymptomatic. Of nine grandchildren who were compound heterozygotes for two mutations in the MEFV gene, only those with either the M694V/V726A or the M694V/M680I genotypes manifested the disease, bearing further evidence to the severity of mutation M694V in individuals sharing a similar genetic and environmental background. Nevertheless, one father and one grandmother who carried the M694V/V726A compound heterozygous genotype were symptom-free, while the four grandchildren with the same genotype manifested the disease from early age, providing further evidence for the role of additional environmental and genetic modifiers. The occurrence of four different mutations in two sets of consanguineous parents merits consideration per se.

Common MEFV mutations among Jewish ethnic groups in Israel: high frequency of carrier and phenotype III states and absence of a perceptible biological advantage for the carrier state

Familial Mediterranean fever (FMF) is an autosomal recessive disease, characterized by recurrent attacks of fever and inflammation of serosal membranes and gradual development of nephropathic amyloidosis. The recent cloning of the FMF gene (MEFV) and identification of disease-associated mutations in most patients made the direct determination of FMF carrier frequency feasible. The aim of the present study was to investigate the carrier rate of the most common MEFV mutations among different Jewish ethnic groups in Israel. Further, an attempt was made to elucidate the possible biological advantage that the heterozygote state may confer. Three hundred Ashkenazi, 101 Iraqi, and 120 Moroccan Jews were screened for the E148Q, V726A, and M694V mutations (at least two most common mutations per group), with a resulting overall carrier frequency in the respective ethnic group of 14%, 29%, and 21%. No difference in morbidity between Ashkenazi carriers and non-carriers of MEFV mutations was discerned, although an excess of febrile episodes in carriers of the V726A and in carriers of either V726A or E148Q was evident (P < 0.02 and P < 0.05, respectively). The frequency of subjects with two MEFV mutations but not expressing FMF (phenotype III) was 1:300 in Ashkenazi Jews and 1:25 in Iraqi Jews, exceeding the reported rate of overt FMF in these ethnic groups by 40-240 fold. These results affirm the high carrier rate among the studied Jewish ethnic groups in Israel and suggest that most subjects with FMF mutations are unaffected.

Two novel mutations R653H and E230K in the Mediterranean fever gene associated with disease

Familial Mediterranean fever (FMF) is an autosomal recessive disorder caused by mutations in the Mediterranean fever gene (MEFV). We describe two novel missense mutations in MEFV, R653H and E230K. Both were found in compound heterozygosity with the mutation M694V in single Turkish patients with clinical syndromes characteristic for FMF. DNA sequencing and PCR-RFLP typing of the families confirmed the mutations and verified recessive modes of inheritance.

The spectrum of Familial Mediterranean Fever (FMF) mutations

Familial Mediterranean Fever (FMF) is the prototype of a group of inherited inflammatory disorders. The gene (MEFV) responsible for this disease, comprises 10 exons and 781 codons. Twenty-nine mutations, most located in the last exon, have been identified so far. It is unclear whether all are true disease-causing mutations. Five founder mutations, V726A, M694V, M694I, M680I and E148Q account for 74% of FMF chromosomes from typical cases (Armenians, Arabs, Jews, and Turks). Rare mutations are preferentially found in populations not usually affected by FMF (eg Europeans not from the above ancestries). The various combinations of MEFV mutations define severe to mild genotypes. The trend is that genotypes including two mutations located within mutational 'hot-spots' (codons 680 or 694) of the gene are associated with severe phenotypes, whereas mild phenotypes are associated with some other mutations, E148Q being the mildest and least penetrant. Understanding the correlation between the FMF phenotype and genotype is further obscured by the existence of complex alleles, modifier loci, genetic heterogeneity and possible epigenetic factors. Additionally, mutations in the MEFV gene are thought to be involved in non FMF disorders. Carrier rates for FMF mutations may be as high as 1:3 in some populations, suggesting that the disease is underdiagnosed. This review update emphasises that both clinical and genetic features are to be taken into account for patient diagnosis, colchicine treatment and prognosis.