Mutation and haplotype studies of familial Mediterranean fever reveal new ancestral relationships and evidence for a high carrier frequency with reduced penetrance in the Ashkenazi Jewish population

The differential contribution of MEFV mutant alleles to the clinical profile of familial Mediterranean fever

Familial Mediterranean fever (FMF) is an autosomal recessive disorder characterised by recurring attacks of fever and serositis. Five sequence alterations (M694V, V726A, M680I, M694I and E148Q), in the MEFV gene, account for the majority of FMF chromosomes. The wide clinical variability of the disease has been related to MEFV allelic heterogeneity. M694V homozygotes have a severe form of the disease. Mutations E148Q and V726A have reduced penetrance. The clinical features, associated with the M680I and the complex V726A-E148Q allele, are not well defined. This study aims to further characterise the phenotypic profile associated with the major MEFV mutations. We investigated 220 FMF patients, in whom both FMF alleles have been identified, and found that different genotypes are characterised by a specific allelic related clinical profile and penetrance. Homozygotes for the M694V mutation and the complex V726A-E148Q allele are the most severely affected and often endure renal amyloidosis. Homozygotes for the M680I and V726A alleles and compound heterozygotes for either the M694V or the V726A-E148Q alleles in combination with either the E148Q, the V726A or the M680I alleles are significantly less severely affected. The morbididity associated with the complex V726A-E148Q allele by far outweighs that associated with the V726A allele, bearing evidence to the fact that the E148Q mutation is not a benign polymorphism. These findings increase our understanding of the role of allelic variability in disease expression.

Study of the mutation M694V of familial Mediterranean fever in Jews

Familial Mediterranean fever (FMF) is a recessively inherited disorder characterized by episodes of fever with abdominal pain, pleurisy, or arthritis. The familial Mediterranean fever gene, designated MEFV, was recently cloned, and the missense mutation M694V accounting for most of the patients with this disease was identified. The objective of the present study was to establish frequencies of the M694V mutation in three groups of Jews. The subjects studied were 381 Sephardi, 256 Ashkenazi, and 65 Oriental Jews, all male subjects, previously collected for an anthropological study, independent of their FMF status. The M694V mutation in the 702 samples was assessed by amplifying genomic DNA with the use of primers that selectively amplify the normal or altered DNA sequence of the M694V mutation, by the amplification refractory mutation system (ARMS). In our sample of Sephardi Jews, the frequency of the M694V mutation is elevated (10.9%), and this is also the case for Oriental Jews (9.2%). In our sample of Ashkenazis, the M694V allele frequency is very low (0.8%).

A genetic profile of contemporary Jewish populations

The Jews are an ancient people with a history spanning several millennia. Genetic studies over the past 50 years have shed light on Jewish origins, the relatedness of Jewish communities and the genetic basis of Mendelian disorders among Jewish peoples. In turn, these observations have been used to develop genetic testing programmes and, more recently, to attempt to discover new genes for susceptibility to common diseases.

Interaction between pyrin and the apoptotic speck protein (ASC) modulates ASC-induced apoptosis

Patients with familial Mediterranean fever suffer sporadic inflammatory attacks characterized by fever and intense pain (in joints, abdomen, or chest). Pyrin, the product of the MEFV locus, is a cytosolic protein whose function is unknown. Using pyrin as a "bait" to probe a yeast two-hybrid library made from neutrophil cDNA, we isolated apoptotic speck protein containing a caspase recruitment domain (CARD) (ASC), a proapoptotic protein that induces the formation of large cytosolic "specks" in transfected cells. We found that when HeLa cells are transfected with ASC, specks are formed. After co-transfection of cells with ASC plus wild type pyrin, an increase in speck-positive cells is found, and speck-positive cells show increased survival. Immunofluorescence studies show that pyrin co-localizes with ASC in specks. Speck localization requires exon 1 of pyrin, but exon 1 alone of pyrin does not result in an increase in the number of specks. Exon 1 of pyrin and exon 1 of ASC show 42% sequence similarity and resemble death domain-related structures in modeling studies. These findings link pyrin to apoptosis pathways and suggest that the modulation of cell survival may be a component of the pathophysiology of familial Mediterranean fever.

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.

Familial Mediterranean fever: prevalence, penetrance and genetic drift

FMF is widely distributed in populations inhabiting the Mediterranean basin. It is mainly attributed to five founder mutations (M680I, M694V, M694I, V726A, E148Q) in the MEFV gene. The frequencies and distribution of these mutations in 146 FMF patients, of Arab and Jewish descent, were compared to that observed in 1173 healthy individuals of pertinent ethnic groups. Five mutations accounted for 91% of FMF chromosomes in our patients. Mutation M694V, predominant in North African Jews, was observed in all patients other than Ashkenazi Jews; mutation V726A was prevalent among all patients other than North African Jews; mutations M694I and M680I were mainly confined to Arab patients. Overall carrier rates, for four mutations (M680I, M694V, V726A, E148Q), were extremely high in our healthy cohort composed of Ashkenazi (n=407); Moroccan (n=243); Iraqi Jews (n=205); and Muslim Arabs (n=318); calculated at 1 : 4.5; 1 : 4.7; 1 : 3.5 and 1 : 4.3 respectively. The V726A allele prevalent among Ashkenazi and Iraqi Jews and Muslim Arabs (carrier rates: 7.4, 12.8 and 7.3%, respectively) was not found among Moroccan Jews. The M694V allele detected among Moroccan and Iraqi Jews and Muslim Arabs (carrier rates 11.1, 2.9 and 0.6%, respectively) was not observed among Ashkenazim. The overall frequency of mutations V726A and E148Q in Ashkenazim, Iraqi Jews and Arabs indicates that the bulk of individuals that comply with the genetic definition of FMF remain asymptomatic.

Mutation frequency of Familial Mediterranean Fever and evidence for a high carrier rate in the Turkish population

Familial Mediterranean Fever (FMF) is a recessive disorder characterised by episodes of fever and neutrophil-mediated serozal inflammation. The FMF gene (MEFV) was recently identified and four common mutations characterised. The aim of this study was to determine the carrier rate in the Turkish population and the mutation frequency in the clinically diagnosed FMF patients. We found a high frequency of carriers in the healthy Turkish population (20%). The distribution of the five most common MEFV mutations among healthy individuals (M694V 3%, M680I 5%, V726A 2%, M694I 0% and E148Q 12%) was significantly different (P<0.005) from that found in patients (M694V 51.55%, M680I 9.22%, V726A 2.88%, M694I 0.44% and E148Q 3.55%).

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.

Incidence of familial Mediterranean fever (FMF) mutations among children of Mediterranean extraction with functional abdominal pain

Of 59 Sephardic Jewish and Arab children in whom functional abdominal pain was diagnosed, we found that 20% were homozygote for the familial Mediterranean fever gene. Inclusion of genetic screening for familial Mediterranean fever may be advisable in the investigation of recurrent abdominal pain among children of Mediterranean extraction.

Familial Mediterranean fever and menstruation

OBJECTIVE

To study the prevalence, the nature and the genotype correlation of menstruation associated familial Mediterranean fever attacks.

METHODS

One hundred and forty-one female patients with familial Mediterranean fever were studied. A questionnaire regarding the presence and nature of menstruation associated with familial Mediterranean fever was designed and filled in by the authors during the patients' visits to the familial Mediterranean fever clinic. The patients who had a positive history for this manifestation were analysed for their familial Mediterranean fever mutations.

RESULTS

Ten out of 141 familial Mediterranean fever female patients (7%) had menstruation-associated familial Mediterranean fever attacks. These patients varied in their disease age of onset and disease duration. Increase of colchicine dose, daily or during the perimenstrual period or oral contraceptives were beneficial in preventing these familial Mediterranean fever attacks. No correlation was found with specific mutations causing familial Mediterranean fever.

CONCLUSIONS

Menstruation-associated familial Mediterranean fever attacks are relatively uncommon. They are not related to the age of the women, the chronicity of their disease or to the mutations they bear. Various therapeutic approaches have to be tried in order to abolish these attacks. A decrease in oestrogen level during menstruation may have a role in this unique manifestation of familial Mediterranean fever.

A single mutated MEFV allele in Israeli patients suffering from familial Mediterranean fever and Behçet's disease (FMF-BD)

Although familial Mediterranean fever (FMF) is an autosomal recessive disorder, preliminary partial mutation analysis suggested that about 60% of FMF patients, who also suffer from Behçet's disease (FMF-BD), have only a single mutated FMF gene (MEFV). In this study, the possibility that patients with FMF-BD may indeed be carriers of a single mutated MEFV is further analysed. The presence of mutations in the coding region of MEFV of eight patients with FMF-BD, representing six families with 47 members, was determined by sequencing. A possible role for the non-carrier chromosome and for BD in the expression of FMF in patients with a single mutated MEFV allele was determined by analysing the association between these variables and the presence of FMF in heterozygous kin. Sequence analysis revealed that all eight patients had indeed only one mutation in the coding region of MEFV. The patients' non-carrier chromosomes converged into three different MEFV haplotypes and were shared by heterozygous unaffected kin in five of six families. BD was found in 10 of 11 carriers with FMF vs one of 16 carriers without FMF (P < 0.001). These results suggest that FMF may be expressed in individuals harbouring only one coding mutation in MEFV. The findings argue against a role for the non-carrier chromosome in the induction of FMF, and suggest that the FMF phenotype in this cohort was associated with the simultaneous presence of BD. These findings may mirror a more generalised rule, that FMF may be precipitated in carriers of a single mutated FMF gene by factors unrelated to the other MEFV allele.

Episodic evolution of pyrin in primates: human mutations recapitulate ancestral amino acid states

Familial Mediterranean fever (FMF; MIM 249100) is an autosomal recessive disease characterized by recurrent attacks of fever with synovial, pleural or peritoneal inflammation. The disease is caused by mutations in the gene encoding the pyrin protein. Human population studies have revealed extremely high allele frequencies for several different pyrin mutations, leading to the conclusion that the mutant alleles confer a selective advantage. Here we examine the ret finger protein (rfp) domain (which contains most of the disease-causing mutations) of pyrin during primate evolution. Amino acids that cause human disease are often present as wild type in other species. This is true at positions 653 (a novel mutation), 680, 681, 726, 744 and 761. For several of these human mutations, the mutant represents the reappearance of an ancestral amino acid state. Examination of lineage-specific dN/dS ratios revealed a pattern consistent with the signature of episodic positive selection. Our data, together with previous human population studies, indicate that selective pressures may have caused functional evolution of pyrin in humans and other primates.

Progressive bouts of acute abdomen: pet the peritoneum

The recent discovery of the mutated gene responsible for Familial Mediterranean Fever (FMF) is supposed to facilitate its diagnosis which up till now is a clinical one because there are no specific laboratory tests. The sensitivity of genetic testing is limited because these tests search only for known mutations. In this case report we describe a patient with periodic abdominal pain in whom the diagnosis of FMF was wrongly discarded because of lack of a durable effect of colchicine and negative genetic testing. Diffuse peritoneal inflammation was nicely demonstrated by a FDG-PET (fluoro-deoxy-glucose positron-emission tomography) performed during a typical crisis. We discuss the possible diagnostic pitfalls and conclude that a crisis-PET might upgrade the level of diagnostic certainty in equivocal cases.

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.

Periodic fever syndromes

The term periodic fever syndrome has been used in a restricted sense to denote two diseases in which episodic fevers occur with a regular periodicity: cyclic neutropenia and the periodic fever, aphthous stomatitis, pharyngitis, and adenopathy (PFAPA) syndrome. Other authors have used the term in a more general sense to encompass a larger group of disorders characterized by recurrent episodes of fever that do not necessarily follow a strictly periodic pattern. These include familial Mediterranean fever, the autosomal dominant familial fevers (also known as Hibernian fever), and the hyperimmunoglobulin D syndrome. This article follows the latter usage, and reviews recent advances in our understanding of the genetics and molecular pathology of this group of diseases, as well as their clinical characterization and treatment.

Phenotype-genotype correlation in 91 patients with familial Mediterranean fever reveals a high frequency of cutaneomucous features

OBJECTIVES

To describe the clinical manifestations of familial Mediterranean fever (FMF) in 91 patients from 47 families and provide data from the genetic study. P:atients and methods. We conducted a retrospective chart review of 91 patients (including 83 children aged <15 yr) from 47 families through a questionnaire and a specific database. The genetic analysis included complete screening of known mutations of the MEFV gene on chromosome 16p13.3. A positive diagnosis required at least two mutations, one on each chromosome.

RESULTS

Our panel included 52 females and 39 males, with a mean age of 7.27 yr. Of the 47 families, 31 were non-Ashkenazi Jews, 10 were Armenians and six were from other ethnic groups. Clinical features included fever (100%), peritonitis (86%), pleuritis (56%), arthritis (34%) and myalgias (27%). We observed a high rate of cutaneous manifestations (47%); erythema, oedema and recurrent oral ulcers were the most frequent. Phenotype-genotype correlations showed a significant association of M694V homozygosity with earlier age of onset (P: = 0.044), fever >39 degrees C (P: = 0. 002), pleural crisis (P: = 0.0044), splenomegaly (P: = 0.0005) and arthritis (P: = 0.001). Associations with mucocutaneous features were as follows: erysipelas-like erythema (P: = 0.012), oedema (P: = 0.61, not significant) and oral ulcers (P: = 0.45, not significant).

CONCLUSION

New phenotype-genotype correlations emerged from our study: homozygosity for the M694V mutation was associated with intensity of fever, splenomegaly and with erysipelas-like erythema. Apart from erysipelas-like erythema, no significant association was found between other cutaneous features and the genotype.

Differential diagnosis of fever of unknown origin in children

Fever of unknown origin in children follows two main clinical patterns, namely fever of unknown origin and chronic episodic fever of unknown origin. Fever of unknown origin is characterized by daily fever persisting for more than 3 weeks. The main causes are infectious, rheumatologic disorders, and malignancy. Chronic episodic fever of unknown origin is characterized by fever lasting for a few days to a few weeks, followed by a fever-free interval and a sense of well-being. The main causes are familial Mediterranean fever, the hyper-immunoglobulin D syndrome, familial Hibernian fever, Behcet disease, the syndrome of periodic fever, aphthous stomatitis, pharyngitis and adenitis, and cyclic neutropenia.

Diagnostic and treatment concerns in familial Mediterranean fever

Familial Mediterranean fever (FMF) is an autosomal, recessively inherited disease, affecting people of Jewish, Arabic, Turkish and Armenian ancestry. The disease is the prototype of the periodic febrile syndromes. Its hallmark is short attacks of fever and painful manifestations in the abdomen, joints, chest, scrotum and skin. Chronic and protracted manifestations, particularly nephropathic amyloidosis, chronic arthritis, and protracted myalgia, may also occur in the disease. The diagnosis of FMF should be considered in individuals of an appropriate ethnic background who present with febrile disease of episodic nature. The differential diagnosis in this case is broad and includes a large number of infectious, inflammatory and genetic diseases. However, in most cases, the very specific general and site-restricted features of the FMF attacks on the one hand, and the absence of manifestations typical of other conditions on the other hand, determine the diagnosis of FMF. This chapter presents clues and tips that help in the diagnosis and treatment of FMF.

MEFV mutations in multiplex families with familial Mediterranean fever: is a particular genotype necessary for amyloidosis?

Familial Mediterranean fever (FMF) is an autosomal recessive disease. It is characterized by recurrent febrile episodes in association with peritonitis, pleuritis, and arthritis. Progressive systemic amyloidosis is the most important complication of FMF that inevitably leads to chronic renal failure. Recently, the gene for FMF, MEFV, has been cloned and four missense mutations have been described: M694V, M680I, V726A, and M694I. Initial studies have suggested that the presence of the M694V mutation carries a significant risk for the development of amyloidosis. In this study, we present seven families, in which at least two individuals have been diagnosed with FMF and at least one with amyloidosis. Among 18 individuals, in whom molecular testing was performed for the four aforementioned mutations, ten had amyloidosis. None of these ten individuals was found to be homozygous for the M694V mutation. In three families, there were two sibs with amyloidosis. None of the sib-pairs with amyloidosis was found to have the same genotype. There were two or more sibs with the same genotype in four families. Only one sib from each family developed amyloidosis in these families. These results provide evidence that FMF patients without the M694V mutation are also at risk for the development of amyloidosis. Particular mutations themselves do not appear to be sufficient to explain the occurrence of amyloidosis in all cases with FMF.

The gene for familial Mediterranean fever, MEFV, is expressed in early leukocyte development and is regulated in response to inflammatory mediators

Familial Mediterranean fever (FMF) is a recessive disorder characterized by episodes of fever and neutrophil-mediated serosal inflammation. We recently identified the gene causing FMF, designatedMEFV, and found it to be expressed in mature neutrophils, suggesting that it functions as an inflammatory regulator. To facilitate our understanding of the normal function of MEFV, we extended our previous studies. MEFV messenger RNA was detected by reverse transcriptase–polymerase chain reaction in bone marrow leukocytes, with differential expression observed among cells by in situ hybridization. CD34 hematopoietic stem-cell cultures induced toward the granulocytic lineage expressed MEFV at the myelocyte stage, concurrently with lineage commitment. The prepromyelocytic cell line HL60 expressed MEFV only at granulocytic and monocytic differentiation. MEFV was also expressed in the monocytic cell lines U937 and THP-1. Among peripheral blood leukocytes, MEFV expression was detected in neutrophils, eosinophils, and to varying degrees, monocytes. Consistent with the tissue specificity of expression, complete sequencing and analysis of upstream regulatory regions of MEFV revealed homology to myeloid-specific promoters and to more broadly expressed inflammatory promoter elements. In vitro stimulation of monocytes with the proinflammatory agents interferon (IFN) γ, tumor necrosis factor, and lipopolysaccharide induced MEFV expression, whereas the antiinflammatory cytokines interleukin (IL) 4, IL-10, and transforming growth factor β inhibited such expression. Induction by IFN-γ occurred rapidly and was resistant to cycloheximide. IFN- also induced MEFV expression. In granulocytes, MEFV was up-regulated by IFN-γ and the combination of IFN- and colchicine. These results refine understanding of MEFV by placing the gene in the myelomonocytic-specific proinflammatory pathway and identifying it as an IFN-γ immediate early gene.

The gene for familial Mediterranean fever, MEFV, is expressed in early leukocyte development and is regulated in response to inflammatory mediators

Familial Mediterranean fever (FMF) is a recessive disorder characterized by episodes of fever and neutrophil-mediated serosal inflammation. We recently identified the gene causing FMF, designatedMEFV, and found it to be expressed in mature neutrophils, suggesting that it functions as an inflammatory regulator. To facilitate our understanding of the normal function of MEFV, we extended our previous studies. MEFV messenger RNA was detected by reverse transcriptase–polymerase chain reaction in bone marrow leukocytes, with differential expression observed among cells by in situ hybridization. CD34 hematopoietic stem-cell cultures induced toward the granulocytic lineage expressed MEFV at the myelocyte stage, concurrently with lineage commitment. The prepromyelocytic cell line HL60 expressed MEFV only at granulocytic and monocytic differentiation. MEFV was also expressed in the monocytic cell lines U937 and THP-1. Among peripheral blood leukocytes, MEFV expression was detected in neutrophils, eosinophils, and to varying degrees, monocytes. Consistent with the tissue specificity of expression, complete sequencing and analysis of upstream regulatory regions of MEFV revealed homology to myeloid-specific promoters and to more broadly expressed inflammatory promoter elements. In vitro stimulation of monocytes with the proinflammatory agents interferon (IFN) γ, tumor necrosis factor, and lipopolysaccharide induced MEFV expression, whereas the antiinflammatory cytokines interleukin (IL) 4, IL-10, and transforming growth factor β inhibited such expression. Induction by IFN-γ occurred rapidly and was resistant to cycloheximide. IFN- also induced MEFV expression. In granulocytes, MEFV was up-regulated by IFN-γ and the combination of IFN- and colchicine. These results refine understanding of MEFV by placing the gene in the myelomonocytic-specific proinflammatory pathway and identifying it as an IFN-γ immediate early gene.

Familial Mediterranean fever: effects of genotype and ethnicity on inflammatory attacks and amyloidosis

OBJECTIVE

The gene causing familial Mediterranean fever (FMF)-an autosomal recessive disease characterized by recurrent short episodes of fever associated most commonly with peritonitis, pleuritis, and arthritis-has recently been found and several mutations identified. The most severe complication of the disease is amyloidosis, which can lead to renal failure. The aim of this study was to investigate the role of genetic versus nongenetic factors on the phenotype as well as on the development of amyloidosis in FMF in a large and heterogeneous group of patients.

METHODOLOGY

We studied 382 patients from 4 ethnic origins living in different environments: North African Jews, other Jews, Turks, Armenians living in the United States, and Armenians from Yerevan, Armenia. Information regarding amyloidosis was available for 371 patients. We examined the association between the mutation M694V and the development of amyloidosis, and we also compared the clinical characteristics of the inflammatory attacks in patients from different ethnic origins, while controlling for the type of mutation.

RESULTS

A significant association was found between amyloidosis and the most common mutation in exon 10 of the FMF gene (MEFV), M694V (for M694V homozygotes, relative risk = 1.77; 95% CI = 1.16-2.71). Amyloidosis was present in 44 of 171 homozygous FMF patients (25.7%), in 22 of 143 compound heterozygous FMF patients (15.4%), and in 7 of 57 patients carrying other mutations (12.3%). In homozygotes for M694V who had not been treated with colchicine before 20 years of age, the risk of amyloidosis developing before this age was 61.0%. In our series, there were no cases of amyloidosis in 16 patients carrying the common mutation E148Q. We found that the type and severity of the FMF inflammatory symptoms were associated with both the genotype and the country of residence of the patient.

CONCLUSIONS

In the light of the high frequency of amyloidosis in homozygotes for the mutation M694V, colchicine treatment should be given to this group irrespective of the severity of the inflammatory attacks to prevent the development of amyloidosis. Our findings also suggest that factors other than genotype, such as environment or genes other than MEFV, play a role in the determination of the severity of the inflammatory attacks in FMF. amyloidosis, specific mutation, phenotype-genotype correlation, ethnicity.

Inflammatory bowel disease in non-Ashkenazi Jews with familial Mediterranean fever

Familial Mediterranean fever and inflammatory bowel disease are two inflammatory conditions. We showed that inflammatory bowel disease was particularly frequent and severe in non-Ashkenazi Jewish patients with familial Mediterranean fever.

Genotype-phenotype correlation in a large group of Turkish patients with familial mediterranean fever: evidence for mutation-independent amyloidosis

OBJECTIVES

Differences in clinical manifestations of familial Mediterranean fever (FMF) between different ethnic groups have been documented. The FMF gene was recently cloned and four missense mutations (Met694Val, Met680Ile, Val726Ala, and Met694Ile) that account for a large percentage of the patients were identified. The results of initial mutation studies have led to the hypothesis that phenotypic variation of the disease may be attributable to the existence of some of these mutations. The purpose of this study was to evaluate whether this phenotypic variation is associated with the existence of particular mutations in Turkish FMF patients living in Turkey.

METHODS

Four missense mutations and genotype-phenotype correlation were investigated in 167 Turkish FMF patients. The patients were grouped according to the presence of the Met694Val and the Met680Ile mutations, and 12 clinical parameters were compared between the groups.

RESULTS

The presence of the Met694Val mutation was not found to be associated with a severe form of the disease or the development of amyloidosis. Arthritis frequency was found to be lower in the patients with homozygous Met680Ile mutation.

CONCLUSIONS

None of the four missense mutations is associated with a severe disease or the development of amyloidosis in Turkish FMF patients living in Turkey. The influence of unknown environmental factors and/or the presence of other genetic changes are necessary to explain the phenotypic variation of the disease and the development of amyloidosis.

The relation between familial Mediterranean fever and amyloidosis

Familial Mediterranean fever (FMF) is the most prevalent type of hereditary recurrent fever. Although the inflammatory attacks that characterize the disease may sometimes be debilitating, reactive amyloidosis remains the most serious manifestation of FMF. Daily treatment with colchicine can prevent both the attacks and amyloid deposition, but FMF-associated amyloidosis has not been eradicated and is still a cause of chronic renal failure in children and adults. The discovery of the gene responsible for FMF, Mediterranean fever gene (MEFV), and of associated mutations represents a major advance that now allows researchers to establish a strong, although nonexclusive association between one specific mutation, M694V, and the amyloid phenotype.

A cholesterol-lowering gene maps to chromosome 13q

A cholesterol-lowering gene has been postulated from familial hypercholesterolemia (FH) families having heterozygous persons with normal LDL levels and homozygous individuals with LDL levels similar to those in persons with heterozygous FH. We studied such a family with FH that also had members without FH and with lower-than-normal LDL levels. We performed linkage analyses and identified a locus at 13q, defined by markers D13S156 and D13S158. FASTLINK and GENEHUNTER yielded LOD scores >5 and >4, respectively, whereas an affected-sib-pair analysis gave a peak multipoint LOD score of 4.8, corresponding to a P value of 1.26x10-6. A multipoint quantitative-trait-locus (QTL) linkage analysis with maximum-likelihood binomial QTL verified this locus as a QTL for LDL levels. To test the relevance of this QTL in an independent normal population, we studied MZ and DZ twin subjects. An MZ-DZ comparison confirmed genetic variance with regard to lipid concentrations. We then performed an identity-by-descent linkage analysis on the DZ twins, with markers at the 13q locus. We found strong evidence for linkage at this locus with LDL (P<.0002), HDL (P<.004), total cholesterol (P<.0002), and body-mass index (P<.0001). These data provide support for the existence of a new gene influencing lipid concentrations in humans.

[Familial Mediterranean fever. New aspects with respect to molecular genetics and pathogenesis revealed in three case reports]

HISTORY AND CLINICAL PRESENTATION

Three young Turkish males were admitted because of acute abdominal pain and fever. All 3 patients had recurrent attacks of these symptoms every few weeks since years with each attack lasting 2 to 3 days. One patient developed a renal amyloidosis with an end-stage renal failure.

DIAGNOSTICS AND CLINICAL COURSE

All patients presented with local abdominal tenderness and an elevation of inflammatory parameters (WBC, ESR, CRP and fibrinogen). X-ray studies, ultrasound and upper endoscopy were normal. In 1 patient histology yielded amyloid fibrils in the antrum of the stomach. In a molecular genetic analysis 2 patients were compound heterozygous for 2 common mutations of the gene responsible for the familial Mediterranean fever (FMF). In all patients the symptoms vanished spontaneously according to an acute attack of FMF. After symptomatic treatment a prophylaxis with colchicine was started.

CONCLUSION

Cloning of the FMF gene and its mutations and identification of the gene product "pyrin" reveals new aspects on genetics and pathophysiology. The improved diagnostic procedure enables an early start of colchicine treatment, especially to prevent renal amyloidosis.

MEFV-Gene analysis in armenian patients with Familial Mediterranean fever: diagnostic value and unfavorable renal prognosis of the M694V homozygous genotype-genetic and therapeutic implications

Familial Mediterranean fever (FMF) is a recessively inherited disorder that is common in patients of Armenian ancestry. To date, its diagnosis, which can be made only retrospectively, is one of exclusion, based entirely on nonspecific clinical signs that result from serosal inflammation and that may lead to unnecessary surgery. Renal amyloidosis, prevented by colchicine, is the most severe complication of FMF, a disorder associated with mutations in the MEFV gene. To evaluate the diagnostic and prognostic value of MEFV-gene analysis, we investigated 90 Armenian FMF patients from 77 unrelated families that were not selected through genetic-linkage analysis. Eight mutations, one of which (R408Q) is new, were found to account for 93% of the 163 independent FMF alleles, with both FMF alleles identified in 89% of the patients. In several instances, family studies provided molecular evidence for pseudodominant transmission and incomplete penetrance of the disease phenotype. The M694V homozygous genotype was found to be associated with a higher prevalence of renal amyloidosis and arthritis, compared with other genotypes (P=.0002 and P=.006, respectively). The demonstration of both the diagnostic and prognostic value of MEFV analysis and particular modes of inheritance should lead to new ways for management of FMF-including genetic counseling and therapeutic decisions in affected families.