0-9
A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z
  • No FAQs found
  • No FAQs found
  • No FAQs found
  • No FAQs found
  • No FAQs found
  • No FAQs found
  • No FAQs found

Familial Mediterranean Fever Mutation Analysis

Test code(s) 16141, 16142 (NY)

Question 1. My patient is symptomatic, but only one mutation has been identified. Is he/she just a carrier? Or, can carriers be symptomatic?

Familial mediterranean fever (FMF) is inherited in an autosomal recessive manner, and two mutations within the MEFV gene are required for symptoms to occur. In most individuals with classic FMF, analysis of the common mutations confirms the diagnosis with the identification of two mutations. The sensitivity for detecting two mutations varies depending on ethnicity: 70% in Arab populations, 90% in Turkish, Armenian or Ashkenazi Jewish populations, and 95% in North African (Sephardic) Jewish populations.

In individuals with non-classic FMF or a mild presentation, additional sequence analysis may be considered, but is not performed at Quest Diagnostics. Please call 866-GENE-INFO to discuss this scenario with one of our genetic counselors.

In all instances in which the clinical picture is suggestive of FMF and molecular testing is not diagnostic, non-classical mutations in the MEFV gene should be considered as well as other autoinflammatory diseases appropriate to the differential diagnosis.

Question 2. My patient has a family history of FMF and has a negative MEFV mutation result. Does this result guarantee that my patient is not a carrier of FMF?

No, please call 866-GENE-INFO to discuss this case with a genetic counselor. Documentation of the specific MEFV mutations in the family will be necessary to determine the accuracy of the testing that was performed on your patient.

Question 3. What does a “heterozygous”, “homozygous”, or “compound heterozygous” result mean?

  • Heterozygous means the individual carries one copy of a mutation on one chromosome.If the mutation is associated with a recessive disease such as FMF, these individuals are called carriers. The carriers are typically unaffected, that is, they show no symptoms of the disease. However, the diagnosis is made clinically, based on1 :
    • Recurrent febrile episodes accompanied by peritonitis, synovitis or pleuritis
    • Recurrent erysipelas-like erythema
    • Repeated laparoscopies for acute abdomen, with no pathology found
    • Amyloidosis of the AA type that characteristically develops after age 15 years in untreated individuals, even those who do not have a history of recurrent inflammatory attacks
    • Favorable response to colchicine
    • Consideration and exclusion of other autoinflammatory diseases

 

If your patient has a clinical diagnosis of FMF, he/she may carry a second MEFV gene mutation not tested for in our panel. Additional mutation testing may be available for your patient at another lab. Call 866-GENE-INFO to discuss this case with a genetic counselor.

  • Homozygous means the individual carries two copies of the same mutation, one on each chromosome. If the mutation is associated with a recessive disease such as FMF, these individuals are typically affected, that is, they show symptoms of the disease. However, the diagnosis is made clinically, based on findings listed above. A homozygous result supports a clinical diagnosis of FMF.
  • Compound heterozygous means the individual carries one copy each of two different mutations, one on each chromosome. If the mutations are associated with a recessive disease such as FMF, these individuals are typically affected. However, the diagnosis is made clinically, based on findings listed above. A compound heterozygous result supports a clinical diagnosis of FMF.

 

References

  1. Familial Mediterranean Fever. GeneReviews. U.S. National Library of Medicine, National Institutes of Health website. http://www.ncbi.nlm.nih.gov/books/NBK1227/. Accessed November 22, 2011.
This FAQ is provided for informational purposes only and is not intended as medical advice. A physician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.
Document: FAQS.17 Revision: 0