RESUMO
Familial Mediterranean Fever (FMF, MIM 249100), or Periodic disease, is a recessively transmitted and ethnically restricted condition prevalent in population from the Mediterranean decent. FMF notoriously has been hard to diagnose until mutations in the MEFV gene have been identified and as a tremendous help are used for the diagnosis of difficult cases. Since FMF can be controlled by medication, it is extremely desirable to have a firm diagnosis. The aim of this study was to establish the frequency of the most common mutations and genotypes in Armenian population. Molecular analysis of MEFV gene mutations in 3000 Armenian patients has demonstrated direct correlation between the clinical severity and the molecular diagnostic criteria of the disease, including the development of renal amyloidosis with MEFV genotypes. MEFV genotyping performed in the framework of a genetic counseling may reveal and identify affected individuals in presymptomatic phase, providing the possibility of a precocious start of the therapy.
Assuntos
Febre Familiar do Mediterrâneo/genética , Adulto , Alelos , Armênia/epidemiologia , DNA/genética , Febre Familiar do Mediterrâneo/epidemiologia , Febre Familiar do Mediterrâneo/patologia , Feminino , Frequência do Gene , Genótipo , Heterozigoto , Humanos , Masculino , Mutação/genética , Fenótipo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Familial Mediterranean fever (FMF) is a recessively inherited disorder predisposing to renal amyloidosis and associated with mutations in MEFV, a gene encoding a protein of unknown function. Differences in clinical expression have been attributed to MEFV-allelic heterogeneity, with the M694V/M694V genotype associated with a high prevalence of renal amyloidosis. However, the variable risk for patients with identical MEFV mutations to develop this severe complication, prevented by lifelong administration of colchicine, strongly suggests a role for other genetic and/or environmental factors. To overcome the well-known difficulties in the identification of modifying genetic factors, we investigated a relatively homogeneous population sample consisting of 137 Armenian patients with FMF from 127 independent families living in Armenia. We selected the SAA1, SAA2, and APOE genes-encoding serum amyloid proteins and apolipoprotein E, respectively-as well as the patients' sex, as candidate modifiers for renal amyloidosis. A stepwise logistic-regression analysis showed that the SAA1alpha/alpha genotype was associated with a sevenfold increased risk for renal amyloidosis, compared with other SAA1 genotypes (odds ratio [OR] 6. 9; 95% confidence interval [CI] 2.5-19.0). This association, which was present whatever the MEFV genotype, was extremely marked in patients homozygous for M694V (11/11). The risk for male patients of developing renal amyloidosis was fourfold higher than that for female patients (OR=4.0; 95% CI=1.5-10.8). This association, particularly marked in patients who were not homozygous for M694V (34.0% vs. 11.6%), was independent of SAA1-allelic variations. Polymorphisms in the SAA2 or APOE gene did not appear to influence susceptibility to renal amyloidosis. Overall, these data, which provide new insights into the pathophysiology of FMF, demonstrate that susceptibility to renal amyloidosis in this Mendelian disorder is influenced by at least two MEFV-independent factors of genetic origin-SAA1 and sex-that act independently of each other.
Assuntos
Apolipoproteínas E/genética , Apolipoproteínas/genética , Febre Familiar do Mediterrâneo/genética , Proteínas/genética , Adolescente , Adulto , Idade de Início , Idoso , Idoso de 80 Anos ou mais , Amiloidose/complicações , Amiloidose/epidemiologia , Amiloidose/genética , Apolipoproteína E4 , Armênia , Criança , Pré-Escolar , Estudos de Coortes , Proteínas do Citoesqueleto , Febre Familiar do Mediterrâneo/complicações , Febre Familiar do Mediterrâneo/epidemiologia , Febre Familiar do Mediterrâneo/etiologia , Feminino , Genótipo , Humanos , Nefropatias/metabolismo , Nefropatias/patologia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Prevalência , Proteínas/fisiologia , Pirina , Fatores SexuaisRESUMO
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.
