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Diseases

Genetic and Rare Diseases Information Center (GARD)

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Familial Mediterranean fever


Other Names for this Disease
  • Benign paroxysmal peritonitis
  • Familial paroxysmal polyserositis
  • FMF
  • Periodic disease
  • Periodic fever
More Names
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Your Question

We recently lost a colleague to Familial Mediterranean Fever. Are his siblings at risk to have inherited this condition? Is genetic testing available to individuals at risk?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

How is Familial Mediterranean Fever (FMF) inherited?

FMF is almost always inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations.[1] As many as 1 in 5 people of Sephardic (non-Ashkenazi) Jewish, Armenian, Arab and Turkish heritage have one mutant copy of the gene and are therefore carriers of FMF, which means they carry the mutant gene but do not suffer from FMF themselves.[2] 

In rare cases, this condition appears to be inherited in an autosomal dominant pattern, in which one copy of the altered gene in each cell is sufficient to cause the disorder and affected individuals often inherit the mutation from one affected parent. However, there are other possible explanations of this apparent pattern. A gene mutation that occurs frequently in a population may result in a disorder with autosomal recessive inheritance appearing in multiple generations in a family, a pattern that mimics autosomal dominant inheritance. If one parent has familial Mediterranean fever (with two mutations in the MEFV gene) and the other parent is an unaffected carrier (with one mutation in the MEFV gene), it may appear as if the affected child inherited the disorder only from the affected parent. This appearance of autosomal dominant inheritance when the pattern is actually autosomal recessive is called pseudodominance.[1]
Last updated: 7/20/2011

What is the chance that a sibling of someone with familial Mediterranean fever will inherit this condition?

A sibling of an individual with familial Mediterranean fever may be at risk for FMF. Their level of risk depends on the genetic status of the parents. This condition is inherited in an autosomal recessive manner, so the parents of an affected individual can either be affected by this condition (they have two copies of the disease-causing mutation), or they are carriers (they only have a single copy of the disease-causing mutation). Carriers do not have symptoms of FMF. The risk for siblings depends on whether both parents are carriers or if one parent has FMF. Genetic testing of the parents may be necessary.[3]
 
If both parents are carriers:

  • Each sibling of an affected individual has a 25% chance of being affected, a 50% chance of being a carrier (no symptoms of FMF), and a 25% chance of being unaffected and not a carrier. 
  • If an individual is unaffected, their chance of being a carrier is 67%.  

If one parent is affected and one parent is a carrier:

  • Each sibling of an affected individual has a 50% chance of being affected and a 50% chance of being as carrier (no symptoms of FMF). 

If an individual is unaffected, their chance of being a carrier is 100%.

Last updated: 6/29/2012

Is genetic testing for Familial Mediterranean Fever available?

GeneTests lists the names of laboratories that are performing genetic testing for FMF. To view the contact information for the clinical laboratories conducting testing, click here
Last updated: 7/20/2011

References