Familial mediterranean fever overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sahar Memar Montazerin, M.D.[2]
Overview
Familial Mediterranean fever, also known as periodic peritonitis or recurrent polyserositis, is a rare monogenic disease with systemic manifestation.
Historical Perspective
Familial Mediterranean fever was first described in a Jewish schoolgirl by Janeway and Mosenthal in 1908. In 1955, Dr. Heller called this disorder familial Mediterranean fever, which refers to its high prevalence in this region and the key presenting feature of periodic fever. The disease was life-threatening before the introduction of colchicine in 1972.
Classification
There is no established system for the classification of familial Mediterranean fever. However, familial Mediterranean fever may be classified according to phenotypic manifestation into three subtypes/groups: type 1, type 2, and type 3.
Pathophysiology
The exact pathogenesis of familial mediterranean fever is not fully understood. However, nearly all the cases are due to a mutation in the MEFV gene, which codes for a protein called pyrin. Normally, pyrin regulates the production of interleukin-1β (IL-1β), an important pro-inflammatory cytokine. When mutation occurs, mutated protein is unable to suppress expression of IL-1β, therefore an inflammatory response would develop results in clinical manifestation of FMF. The disease inherits in an autosomal recessive mode. However, there is an increasing number of data reporting the autosomal dominant inheritance.
Causes
Familial Mediterranean fever is most often caused by a mutation in the MEFV gene. This gene creates proteins involved in inflammation. There are also reports of FMF cases in the absence of causative gene in the genetic screening.
Epidemiology and demographics
The incidence of familial mediterranean fever is estimated 100 per 100,000 individuals worldwide. The prevalence of familial mediterranean fever differs widely according to the geographic area. In the non- Ashkenazi Jews, it ranges from 100 to 400 per 100,000 individuals. Patients of all age groups may develop the familial Mediterranean fever (FMF). However, it usually manifests during Childhood. This disorder usually affects individuals of the Turkish, Armenian, Jewish and Arabic communities. However, it is also common among western societies such as Italy, Greece, Crete, France, and Germany.
Risk factors
There are no established risk factors for familial Mediterranean fever. However, there are some factors which have been observed to trigger the attacks.
Natural history, complications and prognosis
Common complications of familial Mediterranean fever include amyloidosis and increased risk of vasculitic disorders. The prognosis does not differ from that of the general population. However, renal involvement is the determinant factor of patient survival rate.
Diagnosis
Familial Mediterranean fever is primarily diagnosed based on the clinical presentation.
History and Symptoms
The hallmark of familial Mediterranean fever is periodic fever and serositis. A positive history of periodic fever lasting 1 to 3 days and serositis is suggestive of FMF. Common symptoms of familial Mediterranean fever include abdominal pain, episodic fever, arthralgia, chest pain, myalgia, vomiting, and fatigue.
Physical examination
Common physical examination findings of familial Mediterranean fever include fever, arthritis, and skin rash.
Laboratory Findings
An acute phase response is present during attacks, with high C-reactive protein levels, an elevated white blood cell count and other markers of inflammation.
Electrocardiogram
There are no ECG findings associated with familial Mediterranean fever. An ECG may be helpful in the diagnosis of pericarditis, one of the possible manifestations of FMF. Findings on an ECG suggestive of/diagnostic of pericarditis are described here comprehensively.
X-ray
There are no x-ray findings associated with familial Mediterranean fever. However, an x-ray may be helpful in the diagnosis of complications of the disease, which include arthritis, dilatation of the small bowel loops, splenomegaly.
Echocardiography and Ultrasound
There are no echocardiography/ultrasound findings associated with familial Mediterranean fever. However, echocardiography/ultrasound may be helpful in the diagnosis of complications, including pericardial effusion, pleural effusion, and hepatosplenomegaly.
CT scan
There are no CT scan findings associated with familial Mediterranean fever. However, a CT scan may be helpful in the diagnosis of complications of this disease, which include splenomegaly, hepatomegaly, focal peritonitis, and etc.
MRI
There are no MRI findings associated with familial mediterranean fever. However, a MRI may be helpful in the evaluation of complications of this disease, which include hepatosplenomegaly, exertional leg pain, and specifically myalgia.
Other Imaging Findings
There are no other imaging findings associated with familial mediterranean fever.
Other Diagnostic Studies
A genetic test is also available now that the disease has been linked to mutations in the MEFV gene. Sequencing of exons 2, 3, 5, and 10 of this gene detects an estimated 97% of all known mutations.
Treatment
Medical Therapy
The mainstay of treatment for familial Mediterranean fever is medical therapy with colchicine. Exertional leg pain may be treated with NSAIDs. Glucocorticoids may be indicated in case of protracted febrile myalgia. Although there is no alternative for colchicine in case of colchicine resistance, IL-1-blockade may be useful.
Surgery
Surgical intervention is not recommended for the management of familial mediterranean fever. However, since peritonitis is one of the most common manifestations of this disorder, it should be differentiated from other possible causes requiring surgical intervention.
Primary Prevention
There are no established measures for the primary prevention of familial mediterranean fever.
Secondary Prevention
There are no established measures for the secondary prevention of familial mediterranean fever.