What Is Charcot-Marie-Tooth Disease?
Charcot-Marie-Tooth disease (CMT) is an inherited peripheral
nerve disorder. Your peripheral nerves are located on the surface of your brain
and your spinal cord. These nerves connect your central nervous system to the
rest of your body.
CMT was named after the physicians who discovered it in
1886: Jean-Martin Charcot, Pierre Marie, and Henry Tooth. This condition is
sometimes called hereditary motor and sensory neuropathy, or personal muscular
According to the National Institute of Neurological
Disorders and Stroke, CMT is one of the most common inherited neurological
disorders, affecting 1
out of every 2,500 people in the United States.
What Are the Symptoms of Charcot-Marie-Tooth Disease?
Symptoms of CMT normally occur in adolescence, but they can
appear as late as mid-adulthood. CMT affects the nerves that control your voluntary
Common symptoms include:
- weakness of the leg muscles
- difficulty standing
- frequent tripping or stumbling
- difficulty walking
- high stepping when walking
Physical signs include:
- foot deformity (such as hammertoes or high
- inverted lower legs
As CMT progresses, you may experience difficulty moving your
fingers, hands, wrists, feet, and tongue.
What Causes CMT?
CMT is a congenital disease. This means it’s present at
The condition is caused by one or more defective genes. In
most cases, you inherit the defective genes from one or both of your parents.
The defects disturb the function and structure of your peripheral nerve sheaths
and axons. These are the insulating layers around your nerves.
In some rare cases, people are born with CMT spontaneously,
without inheriting a defective gene from their parents.
There are five main types of CMT, and each has its own
- CMT1 is
commonly caused by a duplication of a gene on chromosome 17. This gene controls
the production of your nerves’ protective myelin sheath. CMT1 is also caused by
other gene defects.
- CMT2 results
from a defect in your peripheral nerve cells’ axon. This is caused by a defect
in your mitofusin 2 gene.
also called Dejerine-Sottas disease, is caused by a mutation in your P0 or
PMP-22 gene. This type of CMT is rare.
- CMT4 is
caused by several gene mutations. These genes include GDAP1, MTMR13, MTMR2,
SH3TC2, NDG1, EGR2, PRX, FDG4, and FIG4.
- CMTX is
caused by a point mutation in the connexin-32 protein on your X chromosome.
CMT1 is the most common type of CMT. All types of CMT weaken
the signals travelling from nerves in your extremities to your brain.
To diagnose CMT, your doctor will order tests to help
determine the cause and extent of your nerve damage. These tests may include a
nerve conduction study, electromyography, nerve biopsy, and genetic testing.
conduction study can test the function of electrical signals in your
nerves. During this test, a neurologist will place small electrodes on your
skin. Then, they’ll transmit a small amount of electricity to the electrodes. A
weak response may indicate CMT.
An electromyography test
(EMG) is performed by inserting a thin needle into one of your muscles. This
needle is attached to a wire that connects to a machine. Your doctor will ask
you to flex and then relax your muscle, while the machine measures your
muscle’s electrical activity.
A nerve biopsy is
performed by a surgeon. This procedure involves removing a piece of a nerve
from your calf for testing. This nerve sample is examined for the appearance of
Genetic testing is
used to check for defects in the genes that cause CMT. This is performed using
a sample of your blood.
Physical therapy is a common treatment for people with CMT. It
involves many stretches and light exercises. This therapy helps to increase your
muscle strength and prevent atrophy, or muscle loss.
If you lose function in your extremities, you may be given
assistive devices to help you grab, reach, and push objects. Thumb splints are also
available for people having difficulty grabbing items. You may also be given
orthopedic devices, such as braces and splints, to prevent injuries due to weak
legs and to increase your stability.
If you have a severe foot deformity, it may be treated by a
combination of orthotics (specialized shoes) and surgical corrective
The severity of CMT symptoms varies from one person to
another. CMT can lead to deformities and loss of sensation in your feet. To
help relieve symptoms and prevent complications, inspect your feet daily for
wounds, ulcers, and infections. Wear properly fitted shoes that provide good
ankle support. If you have foot deformities, consider investing in custom-made
To lower your risk of injury and function loss, take good
care of your muscles and joints. For example, stretch regularly and exercise
daily. If you’re unsteady on your feet, consider using a cane or walker to
improve your stability.