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Genetic and Rare Diseases Information Center (GARD)

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Charcot-Marie-Tooth disease type 2F


Other Names for this Disease

  • Charcot Marie Tooth disease type 2F
  • Charcot-Marie-Tooth disease, axonal, Type 2F
  • Charcot-Marie-Tooth disease, neuronal, Type 2F
  • Charcot-Marie-Tooth neuropathy, type 2F
  • CMT 2F
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

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What is Charcot-Marie-Tooth disease type 2F?

Charcot-Marie-Tooth disease type 2F (CMT2F) is a genetic disorder of the peripheral nerves. The subtypes of CMT type 2 (including type 2F) have similar features and are distinguished only by their disease-causing genes. Signs and symptoms usually begin between the ages of 5 and 25 and typically include slowly progressive weakness and atrophy of distal muscles in the feet and/or hands, usually associated with decreased tendon reflexes and mild or no sensory loss. Nerve conduction velocities are usually normal or near-normal. CMT2F is caused by mutations in the HSPB1 gene and is inherited in an autosomal dominant manner. Management may include occupational and physical therapy; special shoes; surgery as needed; mobility aids; and other supportive treatments.[1]
Last updated: 7/31/2012

What are the signs and symptoms of Charcot-Marie-Tooth disease type 2F?

The subtypes of Charcot-Marie-Tooth type 2, including type 2F, have similar signs and symptoms. Affected individuals usually become symptomatic between the ages of 5 and 25, though onset can range from infancy to after the third decade of life. The most common first symptom is weakness of the feet and ankles, followed by slowly progressive weakness and atrophy of distal muscles in the feet and/or hands. Individuals often have decreased tendon reflexes and mild or no sensory loss.

Adults with CMT2 often have bilateral foot drop, symmetric atrophy of muscles below the knee (stork leg appearance) and absent tendon reflexes in the legs. Mild sensory deficits of position, vibration, pain or temperature may occur in the feet, or sensation may be intact. Pain (especially in the feet) is reported by about 20%-40% of affected individuals. Other features that may be associated with CMT2 in a few individuals include hearing impairment; vocal cord or phrenic nerve involvement (which may result in difficulty with speech or breathing); restless legs; and sleep apnea.

CMT2 is progressive over many years, but affected individuals often experience long periods without obvious progression. In some individuals, the condition may be so mild that it goes unrecognized. Affected individuals have a normal life span.[1]
Last updated: 8/1/2012

What causes Charcot-Marie-Tooth disease type 2F?

Charcot-Marie-Tooth disease type 2F (CMT2F) is caused by mutations in the HSPB1 gene. This gene provides instructions for making a protein (heat shock protein beta-1) which helps protect cells under adverse conditions. Heat shock proteins appear to be involved in activities such as cell movement, stabilizing the cell's framework, folding and stabilizing new proteins, repairing damaged proteins, and muscle contraction. Heat shock protein beta-1 is particularly abundant in nerve and muscle cells. In nerve cells, it helps to organize a network of threads that maintain the diameter of axons (neurofilaments), which are needed to transmit nerve impulses efficiently.

It is unclear exactly how HSPB1 mutations lead to the axon abnormalities characteristic of CMT2F. Researchers suggest that mutations lead to an altered protein which clusters together and interferes with nerve cell function. Another possibility is that the altered protein disrupts the assembly of neurofilaments, which in turn may impair the transmission of nerve impulses.
Last updated: 8/1/2012

How is Charcot-Marie-Tooth disease type 2F inherited?

Charcot-Marie-Tooth disease type 2F is inherited in an autosomal dominant manner. This means that only one mutated copy of the gene in each cell is sufficient to cause the condition. Most affected individuals inherit the mutated gene from an affected parent, but in some cases the mutation occurs for the first time in the affected individual (de novo mutation).[1] When an individual with an autosomal dominant condition has children, each child has a 50% (1 in 2) chance to inherit the mutated gene and have the condition.
Last updated: 8/1/2012

Is genetic testing available for Charcot-Marie-Tooth disease type 2F?

Yes. GeneTests lists the names of laboratories that are performing clincial genetic testing for Charcot-Marie-Tooth disease type 2F. To view the contact information for these laboratories, click here. Please note that most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional.
Last updated: 8/1/2012

How might Charcot-Marie-Tooth disease type 2F be treated?

Treatment for Charcot-Marie-Tooth disease type 2 mainly focuses on the specific symptoms present. Affected individuals are often managed by a team of various specialists that includes neurologists, physiatrists, orthopedic surgeons, and physical and occupational therapists.

Depending on the individual's signs and symptoms, the following may be indicated:[1]
  • Special shoes, including those with good ankle support
  • Ankle/foot orthoses (AFO) to correct foot drop and aid with walking
  • Orthopedic surgery to correct severe pes cavus
  • Forearm crutches or canes for stability (fewer than 5% of affected individuals need wheelchairs)
  • Treatment of sleep apnea or restless legs
  • Treatment of pain and depression as needed
Last updated: 8/1/2012

Were can I find the most up-to-date information about Charcot-Marie-Tooth disease type 2F?

To access up-to-date information about Charcot-Marie-Tooth disease type 2F, we encourage you to visit PubMed, a searchable database of biomedical literature. Although not all of the articles are available for free online, most articles listed in PubMed have a summary available. To obtain the full article, contact a medical/university library or your local library for interlibrary loan. You can also order articles online through the publisher’s Web site. Using "Charcot Marie Tooth disease 2" or "Charcot Marie Tooth" (for a broader range of results) as your search term should help you locate articles. Use the Advanced search feature to narrow your search results. Click here to view a sample search.

The National Library of Medicine (NLM) Web site has a page for locating libraries in your area that can provide direct access to these journals (print or online). The Web page also describes how you can get these articles through interlibrary loan and Loansome Doc (an NLM document-ordering service). You can access this page at the following link http://nnlm.gov/members/. You can also contact the NLM toll-free at 888-346-3656 to locate libraries in your area.
Last updated: 8/1/2012

References
Other Names for this Disease
  • Charcot Marie Tooth disease type 2F
  • Charcot-Marie-Tooth disease, axonal, Type 2F
  • Charcot-Marie-Tooth disease, neuronal, Type 2F
  • Charcot-Marie-Tooth neuropathy, type 2F
  • CMT 2F
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.