What is Charcot-Marie-Tooth disease?

Charcot-Marie-Tooth disease, or CMT, is a progressive, degenerative disease involving the peripheral nerves that branch out from the brain and spinal cord to other parts of the body, including the arms, hands, legs and feet. CMT was discovered in 1886 by doctors – Jean-Marie Charcot, Pierre Marie, and Howard Henry Tooth – for whom the disorder was named.

Typically, the brain and nerves are constantly communicating with each other. But with CMT, the motor nerves (the nerves that control our muscles) and sensory nerves (the nerves that carry sensory information like pain and temperature to the brain) don’t work properly. They have trouble sending signals to and from the brain. This results in numbness, sensory loss, muscle weakness/atrophy and nerve degeneration. Over time, the muscles weaken and deteriorate.

Symptoms may begin as early as birth or during adulthood, and they become gradually worse over time. There are currently no treatments or cures for CMT.

What causes CMT?

CMT is caused by genetic mutations. The type of CMT you have is determined by which gene is affected. Thanks to genetic testing and research there are more than 100 known genetic mutations that cause CMT, but most people have one of four most common types of CMT. These subtypes are:

• CMT1
• CMT2
• CMT4
• CMTX

The mutation is always hereditary, meaning it can be passed down from a parent to their child. The mutations originate in families by appearing spontaneously while DNA is forming in a child. Once there is a spontaneous mutation it can then be inherited by future children. CMT is something you are born with — it is not caused by anything you do and it is not contagious.

Symptoms of Charcot-Marie-Tooth (CMT)

The symptoms of Charcot-Marie-Tooth (CMT) and the age when they begin depend on the type of CMT. Some people with CMT start experiencing symptoms as teens or young adults. Other types of CMT can cause symptoms in babies.

CMT symptoms found in teens or young adults:

• Trouble gripping and holding things (sensory loss)
• Tripping and struggling with balance
• Shuffling, marching or dragging the feet when walking
• Cold hands and feet
• Numbness or tingling in the feet or hands
• Curled toes (also called hammertoes)
• High arches in the feet

CMT symptoms found in babies:

• Trouble grasping and holding things
• Taking longer to hold their head up, sit, crawl, stand and walk
• Falling more than babies their same age

Less common symptoms of CMT can include sleep apnea, swallowing problems or choking, hearing loss, scoliosis, and breathing problems (from respiratory muscle weakness).

Treatments for CMT

There are currently no known treatments or cures for Charcot-Marie-Tooth (CMT), but the following can help manage symptoms:
• Pain medication
• Braces or splints that support the feet and ankles
• Custom-made shoes or shoe inserts
• Physical therapy to help the muscles remain strong and flexible
• Occupational therapy to strengthen the muscles used for writing, gripping and other everyday tasks
• Surgery to correct joint deformities
• Hearing aids to help with hearing loss

While no treatments or cures currently exist for CMT, the science to change that does.

Now that scientists know of more than 100 gene mutations that cause CMT, they can work to develop drugs that will target those genes or their functions. The CMT Research Foundation is solely focused on funding CMT research that has the promise to deliver safe and effective treatments for people with all forms of CMT. By pursuing creative and unconventional strategies to advance scientific discovery and partnering with researchers, medical experts, industry leaders and patients, we’re speeding urgently needed progress and answers to families once and for all.

Everything You Need to Know in Five Minutes

Want to better understand CMT, the peripheral nervous system, CMT genetics and therapy development (in language you can actually understand)? Watch these three CMT 101 videos from research expert Dr. Grace Pavlath.