E148Q of the MEFV gene causes amyloidosis in familial Mediterranean fever patients

Clinical features and disease severity of Turkish FMF children carrying E148Q mutation

Background

Familial Mediterranean fever (FMF) is the most common hereditary monogenic autoinflammatory disease caused by mutations in the MEFV gene. It is controversial whether E148Q alteration is an insignificant variant or a disease‐causing mutation. The aim of this study was to evaluate the clinical features and disease severity of FMF patients carrying E148Q mutation.

Methods

Files of FMF patients were retrospectively evaluated. Patients with at least one E148Q mutation were included to the study. The clinical characteristics and disease severity of the patients who were carrying only E148Q mutation were compared with the patients who were compound heterozygous for E148Q and homozygous for M694V mutation.

Results

The study group comprised 33 patients who were homozygous or heterozygous for E148Q; 34 with compound heterozygous E148Q mutations and 86 patients who had homozygous M694V mutation. Patients who had only E148Q mutation were found to have the oldest mean age of disease onset and lowest mean disease severity score. Attack frequency and colchicine doses were lower in patients with only E148Q mutation as compared with the other two groups. The frequency of clinical findings such as fever, abdominal pain, arthralgia, and arthritis among the three groups was similar.

Conclusion

Familial Mediterranean fever patients with only E148Q mutation are presenting with late‐onset and milder disease course despite having similar clinical findings as compared with patients who had other mutations. Finally, we imply that E148Q is a mutation and colchicine treatment should be given.

Prevalence of common MEFV mutations and carrier frequencies in a large cohort of Iranian populations

Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disorder caused by mutations in the MEFV gene. The disease is especially common among Armenian, Turkish, Jewish and Middle East Arab populations. To identify the frequency and the spectrum of common MEFV mutations in different Iranian populations, we investigated a cohort of 208 unselected asymptomatic individuals and 743 FMF patients. Nine hundred and fifty-one samples were analysed for the presence of 12 MEFV mutations by PCR and reverse-hybridization (FMF StripAssay, ViennaLab, Vienna, Austria). Confirmatory dideoxy sequencing of all MEFV gene exons was performed for 39 patients. Fifty-seven (27.4%) healthy individual carried mutant MEFV alleles. Three hundred and ninety-one (52.6%) FMF patients were found positive for either one (172/743; 23.1%), two or three MEFV mutations. Using dideoxy sequencing, three novel variants, A66P, R202W and H300Q, could be identified. Our analysis revealed an allele frequency and carrier rate of 15.6 and 27.4%, respectively, among healthy Iranians. Still moderate compared to neighbouring Armenia, but higher than in Turkey or Iraq, these data suggest that FMF is remarkably common among Iranian populations. E148Q was most frequent in the group of healthy individuals, whereas M694V was the most common mutation among FMF patients, thereby corroborating previous studies on MEFV mutational spectra in the Middle East. Accordingly, MEFV mutations are frequent in healthy Iranian individuals across different ethnic groups. Based on this finding, the awareness for FMF and the implementation of augmented carrier screening programmes considering the multiethnic nature of the Iranian population should be promoted.

Familial mediterranean fever: a fascinating model of inherited autoinflammatory disorder

BACKGROUND

Familial Mediterranean fever (FMF) is a rare inherited autosomal recessive autoinflammatory disorder characterized by recurrent and self-limited episodes of fever and painful serositis, lasting 1-3 days. FMF occurs almost exclusively among ethnic groups of the Mediterranean basin, although cases have also been found in Japan and Korean populations. Diagnosis is based on clinical features, response to colchicine and genetic analysis. Novel drugs are emerging, allowing better management of colchicine-resistant/colchicine-intolerant patients. This review aims to attract the attention of the readers on differential diagnosis and management of patients with FMF.

METHODS

The current state-of-the-art on FMF is outlined, with respect to epidemiological, genetic, pathophysiological and therapeutic characteristics, based on critical analysis of solid scientific literature.

RESULTS

FMF is more frequent than it was thought before. The phenotypic expression of M694V is more severe than that of V726A. Patients with M694V/M694V homozygosity are exposed to a higher risk of developing renal amyloidosis, arthritis, dermatologic and oral lesions, higher fever and more frequent painful attacks. Life-long therapy with colchicine (1·0-2·4 mg/day) is effective and safe to prevent recurrent attacks and renal amyloidosis and to reverse proteinuria. In nonresponder patients, alternative novel approaches include interleukin-1 receptor antagonist anakinra and the interleukin-1 decoy receptor rilonacept.

CONCLUSIONS

The prognosis of FMF is normal if AA amyloidosis is prevented. Colchicine remains the first-line therapy to treat pain and prevent amyloidosis. A follow-up should include clinical evaluation, therapeutic adjustments, measurement of serum amyloid A and proteinuria.

E148Q is a disease-causing MEFV mutation: a phenotypic evaluation in patients with familial Mediterranean fever

BACKGROUND

Familial Mediterranean fever (FMF) is one of the periodic fever syndromes. It is common among Turks, Jews, Arabs, and Armenians. Several mutations in the MEFV gene, including E148Q, have been identified as causing this disease. It has been suggested that the E148Q mutation is the mildest mutation and some reports have questioned its disease association.

OBJECTIVE

To evaluate the phenotypic features of the patients with E148Q mutation.

SUBJECTS

26 patients homozygous for E148Q, 10 compound heterozygous for E148Q, and eight complex cases were assessed.

RESULTS

Although four of the 26 patients with E148Q/E148Q were asymptomatic at the time of evaluation, abdominal pain was seen in 77% of the patients, fever in 66%, arthralgia in 50%, arthritis in 15.4%, and vomiting in 23.8%. Compound heterozygotes and complex cases had a higher frequency of abdominal pain, fever, arthralgia, arthritis, myalgia, and chest pain than subjects who were homozygous for E148Q, but none of these symptoms reached statistical significance. None of our patients had amyloidosis but two with E148Q/E148Q had a family history of amyloidosis and one had rapidly progressive glomerulonephritis secondary to vasculitis, which progressed to chronic renal failure.

CONCLUSIONS

Patients homozygous for E148Q have a heterogeneous clinical presentation. Most are symptomatic and colchicine treatment is required in these patients.