Chromosomal and Genetic Conditions

Charcot-Marie-Tooth Disease

What is Charcot-Marie-Tooth disease?

Charcot-Marie-Tooth (CMT) disease is a group of genetic conditions that affect peripheral nerves. These are nerves that leave your child’s brain or spinal cord and branch into distant parts of your child’s body, like their arms and legs.

CMT affects both main types of peripheral nerves:

  • Motor nerves, which control the muscles your child uses to walk, move, use their hands and breathe
  • Sensory nerves, which sense touch, pain, warm and cold

In CMT, 1 or both of these problems happens:

  • The long, thin nerve fibers (axons) that branch from your child’s brain or spinal cord don’t carry signals as well as they should.
  • The cover (myelin) that should protect your child’s axons doesn’t work well, so your child’s nerve signals travel slowly.

CMT is named for the 3 doctors who first identified it. (It does not have anything to do with teeth.) It’s also known as hereditary motor and sensory neuropathy.

  • Over time, your child’s peripheral nerves are damaged and they can’t move signals back and forth normally.

    Your child’s muscles – mainly the muscles farther from their spinal cord, in their feet, legs, hands and forearms – become weaker and smaller (atrophy) because they aren’t getting strong signals to move. 

    Your child might also have trouble sensing how their hands and feet feel, such as not noticing if they get a cut or blister.

    There are several types of CMT that can cause more or less weakness, atrophy and sensory problems.

  • CMT happens if there’s a problem with a gene that makes proteins needed in your child’s axons or myelin.

    Many different genes can cause different types of CMT.

    In most cases, a child develops CMT after they inherit an abnormal gene from their parents. For some types of CMT, only 1 parent needs to pass along the gene. Other types of CMT happen only if both parents pass along the gene. Much less often, a child develops an abnormal gene that causes CMT even though neither parent had the gene.

  • Children with CMT are born with an abnormal gene that affects their axons or myelin.

    Usually symptoms start in teens or young adults. In some types of CMT, symptoms may start in younger children or babies or not until later in adulthood.

  • Doctors group CMT into types based on which gene causes it.

    Most types are numbered based on how the child is affected, how the abnormal gene is passed down or how well the nerves carry signals.

    • CMT1: The gene is passed from only 1 parent. It causes a missing protein in the myelin.
    • CMT2: The gene is passed from only 1 parent. It causes a missing protein in the nerve axon.
    • CMT3: The gene is passed from both parents. It causes a missing protein in the myelin. This type affects younger children with more serious disease. It is also called Dejerine-Sottas disease, congenital hypomyelinating neuropathy or severe, early-onset CMT.
    • CMT4: The gene is passed from only 1 parent. It can affect either the myelin or the axon.
    • CMTX: This type is caused by gene changes on the X chromosome.

    Some types are further divided into subtypes by adding a letter at the end, such as CMT1A, CMT1B and CMT1C. This means doctors have found the specific genetic cause.

    Your child’s healthcare team can explain which type your child has and what it may mean for your child and family.

  • Each child with CMT is unique. One thing they all have in common is some degree of muscle weakness.

    The age when symptoms start and the exact effects on a child can vary widely. Even within your family, your child may have less serious or more serious symptoms than a relative with CMT. Typically, movement and feeling get worse slowly over time.

    CMT almost never affects a child’s brain, intelligence or ability to think and learn. It doesn’t affect their emotions or ability to have relationships with family and friends.

    There is no cure yet for the disease, but together you and your child’s healthcare team can support your child’s function and comfort so they have a rich, active life at home, at school and in the community.

    Most children with CMT have a normal life span.

Charcot-Marie-Tooth Disease at Seattle Children’s

Seattle Children’s Neuromuscular Program offers the most comprehensive care in the Pacific Northwest for children with Charcot-Marie-Tooth disease. 

    • We have been named an MDA Care Center by the Muscular Dystrophy Association, a leading advocacy group for people with CMT.
    • Our dedicated team – doctors, nurse practitioners, therapists, dietitians, genetic counselors, orthotists and social workers – has expertise and experience in diagnosing and treating CMT.
    • Seattle Children’s brings together pediatric specialists from Rehabilitation Medicine, Neurology, Orthopedics and, if needed, Pulmonary and Sleep Medicine to evaluate your child’s unique needs.
    • We design and provide care to help your child and family manage CMT and to give your child the best possible function and quality of life now and as they grow.
    • Seattle Children’s provides a full range of treatments, from medicines, therapy and equipment to orthopedic surgery.
    • To make sure your child has a full evaluation and receives complete, coordinated care, we will involve experts from across Seattle Children’s.
    • Your child may see their entire team on a single day, making the process easier on you and your child.
    • Based on your child’s needs, your team may include experts from other specialties and programs.

Symptoms of Charcot-Marie-Tooth Disease

Children with CMT usually start to show signs and symptoms in their teen years or as young adults, but sometimes symptoms start earlier or later.

Symptoms can range widely from mild to serious. Even within families, there are differences. Usually symptoms begin in the feet and legs.

    • Weak leg, ankle and foot muscles that might cause foot drop and make your child walk with an awkward or high step, trip and fall
    • Loss of muscle (atrophy), which might make the lower leg look thinner than usual
    • Weak hand muscles, which might cause problems with writing or holding onto objects
    • Bone and joint problems, such as toes bent at the middle joint (hammertoe) and high arches (cavus foot), caused by stronger muscles pulling against weaker muscles (muscle imbalance)
    • Loss of some feeling in the feet and hands
    • Numbness, tingling or burning feeling, usually mild
    • Pain from nerve damage or muscle cramps
    • Scoliosis, kyphosis or problems with the hip bone and socket (hip dysplasia) caused by muscle imbalance
    • Trouble breathing, swallowing or speaking, if CMT affects nerves that control the muscles used in these actions

Diagnosing Charcot-Marie-Tooth Disease

Your child’s doctor will most likely schedule a clinic visit to:

  • Ask you about your child’s symptoms, development and medical history and whether anyone else in your family has had the same kind of symptoms
  • Examine your child and look for common signs of CMT, such as:
    • Muscle weakness
    • Loss of muscle
    • Reduced reflexes
    • Bone or joint problems
    • Loss of feeling

Your child may need 1 or more of these tests to get more information:

  • Electromyogram and nerve conduction velocity (EMG/NCV) studies.
  • Genetic test, done with a blood sample, to find some of the gene changes that cause CMT. (Tests don’t exist for all types of CMT.)
  • Nerve biopsy to see whether your child’s nerves or myelin is abnormal.
  • X-ray to check for bone problems.

Seattle Children’s also offers genetic counseling and testing for parents and other family members of children with CMT.

Treating Charcot-Marie-Tooth Disease

At Seattle Children’s, your child receives complete care from the team in our Neuromuscular Program and from our other programs if needed.

We offer a range of treatments to support your child’s health, comfort and ability to be as healthy, active and independent as they can.

Every child with CMT does not need every type of treatment. Your child’s treatment plan will be custom-made for them and will change over time as their needs change.

Together, you, your child and your healthcare team will set goals and make care choices to give your child the best quality of life and help them learn and grow to their fullest.

  • The Neuromuscular Program team includes experts from Rehabilitation Medicine, Endocrinology, Neurology, Pulmonary and Sleep Medicine and the Heart Center, as well as dietitians, genetic counselors and social workers.

    Based on your child’s needs, we involve specialists from other clinics and programs around Seattle Children’s, such as:

  • Common treatments to maintain your child’s ability to move and do the things they want to do include:

    • Physical therapy for strength, flexibility, balance, stamina and general health and to evaluate whether your child needs equipment 
    • Occupational therapy to help your child with activities like writing, dressing and using a computer keyboard
    • Aquatic therapy, done in a pool, where water supports your child’s body
    • Boots, high-top shoes or braces for your child’s ankles and feet to help them walk more easily or braces for their thumbs to provide support
    • Medicines to help with pain, if your child has any pain from CMT
    • If needed, devices that help your child walk or get around, such as a cane, walker, wheelchair or motorized scooter
  • CMT doesn’t usually affect breathing muscles. If it affects your child’s breathing, we will evaluate how well your child’s lungs work and provide care they need to support breathing.

    Some people with CMT may need a machine to help with breathing (bilevel positive airway pressure [Bi-PAP] or continuous positive airway pressure [CPAP]) at night.

  • A dietitian and others on your child’s team will work with you and your child to make sure your child gets the nutrition they need for the best growth and development.

  • A social worker focuses on supporting your child and family and helps with coping, social relationships, behavior and emotions. Along with your child’s doctors, nurses and therapists, the social worker will connect you with helpful resources at Seattle Children’s and in the community.

Contact Us

Contact the Neuromuscular Program at 206-987-2114 for a referral, a second opinion or more information.