Eldad Ben-Chetrit

A candidate gene for familial Mediterranean fever

Familial Mediterranean fever (FMF) is an autosomal recessive disorder characterized by attacks of fever and serositis. In this paper, we define a minimal co-segregating region of 60 kb containing the FMF gene (MEFV) and identify four different transcript units within this region. One of these transcripts encodes a new protein (marenostrin) related to the ret-finger protein and to butyrophilin. Four conservative missense variations co-segregating with FMF have been found within the MEFV candidate gene in 85% of the carrier chromosomes. These variations, which cluster at the carboxy terminal domain of the protein, were not present in 308 control chromosomes, including 162 validated non-carriers. We therefore propose that the sequence alterations in the marenostrin protein are responsible for the FMF disease.

Familial Mediterranean fever.

The international consortium detected a full-length transcript of 3·7 kb encoding a protein consisting of 781 aminoacids. This protein product was termed “pyrin”, indicating its relation to fever, the hallmark of FMF. The French consortium isolated a 1·9 kb complementary DNA sequence coding partly a protein they named “marenostrin” (“our sea”), in reference to the Mediterranean focus of FMF. Several conservative missense mutations were discovered in exon 10 of the gene at its carboxyterminal site. Three identical mutations were reported by both research groups (panel 1); the French consortium detected a fourth. The gene was novel, with no sequence identities in the protein database. One of these three mutations was found in 85% of carrier chromosomes so about 15% of FMF carrier chromosomes do not yet have demonstrable mutations. Additional mutations in exon 2 of the gene have recently been detected in several families from various ethnic groups.

Genome-wide association study identifies variants in the MHC class I, IL10, and IL23R-IL12RB2 regions associated with Behcet's disease

Behçets disease is a genetically complex disease of unknown etiology characterized by recurrent inflammatory attacks affecting the orogenital mucosa, eyes and skin. We performed a genome-wide association study with 311,459 SNPs in 1,215 individuals with Behçets disease (cases) and 1,278 healthy controls from Turkey. We confirmed the known association of Behçets disease with HLA-B*51 and identified a second, independent association within the MHC Class I region. We also identified an association at IL10 (rs1518111, P = 1.88 × 10−8). Using a meta-analysis with an additional five cohorts from Turkey, the Middle East, Europe and Asia, comprising a total of 2,430 cases and 2,660 controls, we identified associations at IL10 (rs1518111, P = 3.54 × 10−18, odds ratio = 1.45, 95% CI 1.34–1.58) and the IL23R-IL12RB2 locus (rs924080, P = 6.69 × 10−9, OR = 1.28, 95% CI 1.18–1.39). The disease-associated IL10 variant (the rs1518111 A allele) was associated with diminished mRNA expression and low protein production.

COLCHICINE: 1998 UPDATE

OBJECTIVE To present an update of the use of colchicine in patients with familial Mediterranean fever (FMF) and other rheumatic and nonrheumatic diseases. DATA SOURCES Published studies on colchicine retrieved from MEDLINE searches from 1987 to 1997 and reports presented at national and international meetings. STUDIES SELECTION AND EXTRACTION: All studies were reviewed by the authors. Reports addressing the topics of colchicine pharmacokinetics, biological effects, indications for use, and side effects were selected. DATA SYNTHESIS Colchicine is an alkaloid that may interfere with microtubule formation, thereby affecting mitosis and other microtubule-dependent functions. It has a bioavailability of 25% to 50% when administered orally. Colchicine and its metabolites are excreted through the urinary and biliary tracts. It may be used while breast feeding; however, amniocentesis should be performed when used in pregnancy. The drug may be given to children with FMF. The efficacy of colchicine has been proved in FMF, gout, Behcets disease, and cirrhosis. Its place in the treatment of scleroderma, sarcoidosis, and skin disorders remains to be determined. Gastrointestinal side effects occur early and are most common manifestations of colchicine toxicity. Severe colchicine toxicity results in multiple organ failure, convulsions, coma, and death. Potentially, effective treatment with Fab anti-colchicine antibodies unfortunately is unavailable; therefore, treatment is supportive. CONCLUSIONS Colchicine is a relatively safe and effective medication for several disorders when used in appropriate dosage in patients with normal kidney and liver function.

PROLONGED ATYPICAL ILLNESS ASSOCIATED WITH SEROLOGICAL EVIDENCE OF PERSISTENT EPSTEIN-BARR VIRUS INFECTION

Seven patients with prolonged atypical illness were followed up for more than a year. Sera taken during that period showed significantly increased titres of IgM antibodies against the viral capsid antigen (VCA) of Epstein-Barr virus (EBV). In four of the patients antibodies to the R component of the early antigen (EA) complex of EBV were clearly detectable. Only one of these seven patients had presented with symptoms of classic infectious mononucleosis. Serological and clinical observations in these patients suggest that the prolonged atypical illness was probably the result of persistent EBV infection.

Isolation and characterization of a cDNA clone encoding the 60-kD component of the human SS-A/Ro ribonucleoprotein autoantigen.

SS-A/Ro is a nucleocytoplasmic ribonucleoprotein (RNP) particle that is a common target of autoimmune response in Sjögrens syndrome (SS) and systemic lupus erythematosus (SLE). Previously, SS-A/Ro has been shown to be composed of at least two polypeptide antigens of 60 and 52 kD noncovalently associated with a set of small RNAs, designated Y1-Y5. A serum from an SS patient was selected to screen a lambda gt11 cDNA library constructed from human T cell lymphoblastic leukemia (MOLT-4) mRNA. An immunoreactive clone was isolated that possessed a 1.8-kb cDNA insert. In vitro transcription and translation of the cDNA resulted in the synthesis of a 57.5-kD polypeptide which was specifically immunoprecipitated by SS-A/Ro antisera. The identity of the cDNA encoded protein as the 60-kD SS-A/Ro antigen was established by proteolytic peptide mapping of the cDNA-encoded protein and the 60-kD HeLa cell antigen. The sequence of the cDNA shows that the 60-kD SS-A/Ro protein possesses both RNA binding protein consensus sequences and a single zinc-finger motif. Recombinant SS-A/Ro antigen produced in bacteria proved to be a sensitive and specific reagent for detection of anti-SS-A/Ro antibodies in patient sera. The availability of the 60-kD SS-A/Ro cDNA will enable detailed analysis of the molecular structure and function of the SS-A/Ro RNP particle and its role in autoimmune pathology.

Familial Mediterranean Fever in the World

Introduction Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent episodes of fever accompanied by peritonitis, pleuritis, arthritis, or erysipelas-like erythema (1,2). A typical FMF attack lasts approximately 3 days. The frequency of episodes varies from once every week to several times a year. One of the devastating complications of FMF is the development of serum amyloid A (SAA) amyloidosis, which mainly affects the kidneys but may involve other organs. Since 1972, colchicine has been the treatment of choice for FMF (3). It controls the acute attacks and prevents the development of amyloidosis. The disease is prevalent among populations surrounding the Mediterranean Sea. However, in recent years, more and more cases have been reported in countries not related or close to this area, such as the US and Japan. This observation raised the question as to the real prevalence of FMF in countries other than those around the Mediterranean basin and to its clinical characteristics in these countries. Furthermore, it poses a challenge to find out the ethnic origin of these patients and to study whether their disease behaves similarly to that in the countries commonly associated with FMF. FMF may display a different clinical picture among various populations, and these differences reflect the change in the repertoire of mutations among the specific populations. In this review, we will try to look for and explain the origin of FMF in countries far from the Mediterranean and Middle East regions. We will also compare the nature of the disease in these countries and find out whether they differ from the FMF manifestations, treatment, and prognosis in patients surrounding the Mediterranean Sea. Prevalence of FMF in the world FMF is almost always restricted to Turks, Armenians, Arabs, and non-Ashkenazi Jews. It is quite a rare disease in the rest of the world, although patients with FMF have been reported in European countries such as France, Germany, Italy, and Spain, as well as in the US and Australia (2,4). The exact frequency of FMF among the various populations is not always available because formal epidemiologic studies have not been done. Nevertheless, a rough estimate regarding the prevalence of the disease can be obtained by gathering details from different studies and sources (Figure 1). Turkey is probably the country with the highest number of FMF patients in the world. Since the prevalence of FMF is approximately 1:400 to 1:1,000 (highest in the areas of Anatolia) and the population is approximately 70 million, it is estimated that Turkey has more than 100,000 patients with FMF (4–6). In Israel, the prevalence is slightly more than 1:1,000 (depending on the ethnic group), and since the population is approximately 7 million, it is estimated that there are approximately 10,000 patients (7). Armenia is probably the next country with widespread FMF. It is estimated that the prevalence of FMF is approximately 1:500 and with a population of 3 million, the total number of patients is approximately 6,000 (8). Other countries in the Middle East such as Jordan, Syria, and Lebanon have many FMF patients, but their exact number is not known (9,10). In addition to the above countries, FMF is found in significant numbers in North African countries, Greece, Crete, France, Germany, Italy, and the US (11–14). In recent years, approximately 100 cases have been reported in Japan (15, 16, and Tsuchiya-Suzuki A, et al: unpublished observations). On the other hand, there are countries where FMF has not been found or reported. These include sub-Saharan African countries, Ethiopia, Yemen, and Scandinavian states, as well as South Asian and Far Eastern countries such as India and Thailand. The identification of the MEFV gene associated with FMF and the prevalence of its mutations in the different ethnic groups allowed some hypotheses on the phylogeny of the disease (12).

Phenotype-genotype correlation in Jewish patients suffering from familial Mediterranean fever (FMF)

Familial Mediterranean Fever is one of the most frequent recessive disease in non-Ashkenazi Jews. The gene responsible for the disease (MEFV) has very recently been identified. The M694V (‘MED’) mutation was found in about 80% of the FMF Jewish (Iraqi and North African) chromosomes. To see if the presence of this mutation could be correlated with particular traits of the disease, we examined a number of clinical features in a panel of 109 Jewish FMF patients with 0, 1 or 2 MED mutations. We showed that homozygosity for this mutation was significantly associated with a more severe form of the disease. In homozygous patients, the disease started earlier (mean age 6.4 +/− 5 vs 13.6 +/− 8.9) and both arthritis and pleuritis were twice as frequent as in patients with one or no M694V mutation. Moreover, 3/3 patients with amyloidosis displayed two MED mutations. No association was found with fever, peritonitis, response to colchicine and erysipeloid eruption. The present result strongly suggests the potential prognostic value of the presence of this mutation.

The E148Q mutation in the MEFV gene: is it a disease-causing mutation or a sequence variant?

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of serositis. To date more then 18 mutations responsible for the disease were identified in the MEFV gene, one such a mutation is E148Q in exon 2 of the gene. While screening FMF patients for mutations in the MEFV gene, we have identified 2 individuals parents of 2 unrelated FMF patients, who were homozygous for E148Q mutation. Upon clinical examination they were absolutely disease free and therefore raised the possibility that this mutation is a benign polymorphism rather than a mutation causing disease. To further investigate the role of the E148Q in FMF we analyzed 25 parents of FMF patients and a control group of 70 individuals, Jews of Moroccan extraction to match for ethnicity of the patients. The rate of E148Q in the control group was 6.4%, being 7.8% among the patient group. Among the parents group (obligatory carriers), in addition to the 2 parents that were homozygous E148Q, in 2 families one of the parents was heterozygote for E148Q but transmitted the other allele (apparently with unknown FMF mutation) to the affected child. Two healthy sibs of one of the E148Q homozygous were also homozygous E148Q. These observations are not in accordance to the notion that E148Q is a mutation causing disease. Hum Mutat 15:385–386, 2000.

Colchicine prophylaxis in familial Mediterranean fever: reappraisal after 15 years.

As determined in this study of 45 patients, the prolonged use of colchicine therapy in familial Mediterranean fever (FMF) is safe and effective in preventing flares of FMF and amyloidosis. It has acceptable adverse effect profile and can be used in children and pregnant women. Its discontinuation predisposes patients to acute FMF attacks and the development of amyloidosis. Articular involvement is less responsive to colchicine and may require therapy with nonsteroidal antiinflammatory drugs.