Charcot-Marie-Tooth Disease

What is Charcot-Marie-Tooth Disease?

Charcot-Marie-Tooth disease (CMT) or hereditary motor and sensory neuropathy (HMSN) is a common neurological disorder that causes muscle weakness and nerve damage in the legs and arms. CMT is caused by a mutation in genes that create proteins for the nervous system.

These mutations affect peripheral nerve axons, or parts of nerve cells in which convey electrical signals, and they affect myelin sheaths, which insulates nerve cells. Because CMT is caused by genetic mutations, doctors will look at a patient’s family history along with a medical history and examination to diagnose the disease.

What are the Symptoms of Charcot-Marie-Tooth Disease?

CMT usually manifests itself during adolescence or early adulthood. Some symptoms include an abnormal gait, hammertoes, high foot arches, muscle weakness and atrophy, scoliosis, decreased sensation, tremors, gastrointestinal disorder, weak vocal cords, and malformed hip sockets.

Charcot-Marie-Tooth Disease Causes

Charcot-Marie-Tooth disease is caused by genetic mutations that affect the nerves in a person’s extremities – feet, legs, arms and hands. These mutations either damage the nerves themselves or the protective coating surrounding the nerves (called the myelin sheath).

Each of the five forms of Charcot-Marie-Tooth disease is caused by a different mutation, with some forms caused by several different mutations:

  • CMT1 by duplication of the gene on chromosome 17 that controls production of the myelin sheath
  • CMT2 by defect in the mitofusin 2 gene (which in turn creates a defect in the peripheral nerve cells’ axons)
  • CMT3 (or Dejerine-Sottas disease) by mutation in the P0 or PMP-22 gene
  • CMT4 by mutations in several genes, including the GDAP1, MTMR13, SH3TC2, NDG1, EGR, PRX, FDG4, and FIG4
  • CMTX by mutation in the connexin-32 protein on the X chromosome

These mutations are hereditary, and symptoms typically appear during adolescence and early adulthood. It is only in rare cases that Charcot-Marie-Tooth disease occurs in someone who does not have a family history of the condition. The overall condition is no more likely to occur in men than women, or in one ethnic group over another.

How is Charcot-Marie-Tooth Disease Treated?

Unfortunately CMT is a progressive disease that has no cure; however, most patients can expect a normal lifespan and increased functionality/mobility with treatment. Occupational therapy, physical therapy, exercising, and stretching can greatly increase the quality of life for patients. Orthopedic supports, like splints and braces, can help people be more mobile without weakness or pain.

People with CMT should always consult with their doctor before taking a medication. There are neurotoxic medications and supplements that can actually exacerbate the symptoms.

Charcot-Marie-Tooth Disease Prevention

Research is ongoing for Charcot-Marie-Tooth disease, as well as other muscular dystrophy related conditions, but there is no way known to prevent the condition from occurring at this point in time.

If there is a family history of Charcot-Marie-Tooth disease, genetic testing can be done to determine if a person carries the mutation, or if they will be affected and which form they will be affected by. This testing will not stop the condition from occurring. However, early detection can lead to the development of a treatment plan to manage it and prevent it from completely debilitating the individual diagnosed with it.