Charcot-Marie-Tooth disease (CMT) is the most common inherited nerve disorder, affecting about 1 in 3,300 people worldwide and an estimated 150,000 people in the United States. It damages the peripheral nerves, the long cables that carry signals between your brain and spinal cord and the rest of your body, leading to progressive weakness and numbness that typically starts in the feet and hands. CMT isn’t usually life-threatening, and most people with it have a normal life expectancy.
How CMT Affects the Body
CMT is a length-dependent nerve disorder, meaning it hits the longest nerves first. Because the nerves running to your feet and lower legs are the longest in the body, that’s where symptoms almost always begin. Over time, the disease can work its way up to the hands and forearms. The core problem is that damaged nerves can’t properly send signals to muscles or relay sensation back to the brain, so both strength and feeling gradually decline in the affected areas.
The hallmark physical signs include high-arched feet (called pes cavus), curled or hammertoes, and progressive wasting of the calf and lower thigh muscles. This muscle loss can create a distinctive tapering of the lower legs sometimes called “stork leg deformity.” In the hands, long-standing disease can cause subtle wasting of the small muscles, making fine motor tasks like buttoning a shirt or writing more difficult. Some people also develop scoliosis (curvature of the spine).
Walking problems are common and come from several directions at once: weakened muscles, loss of position sense in the feet, and the structural changes caused by high arches and hammertoes. Foot drop, where the front of the foot can’t be lifted properly during a step, is one of the most recognizable gait issues. People with CMT often report muscle cramps, reduced reflexes, and a general sense of instability on their feet. These foot deformities are a major source of disability over the course of the disease.
When Symptoms Typically Appear
CMT usually becomes apparent during adolescence or early adulthood, though it can show up anytime from early childhood through late adulthood. In children, early clues might include delayed motor milestones, clumsiness, or difficulty keeping up physically with peers. The progression is slow, usually measured in years or decades rather than months, and the severity varies enormously. Some people have mild symptoms they barely notice, while others eventually need braces or mobility aids.
Types of CMT
CMT is actually a family of related conditions grouped by how they damage nerves. The two broadest categories are CMT1 (demyelinating) and CMT2 (axonal), and the distinction matters because it points to different underlying genetic causes.
In CMT1, the problem is the myelin sheath, the insulating layer that wraps around nerve fibers and helps signals travel quickly. When myelin breaks down, nerve signals slow dramatically. On a nerve conduction test, people with CMT1 typically show speeds below 35 meters per second, compared to a normal range above 40 to 45 meters per second. CMT1A, the single most common subtype, accounts for roughly half of all CMT cases and is caused by an extra copy of a gene called PMP22 on chromosome 17.
In CMT2, the myelin is relatively intact, but the nerve fiber itself (the axon) degenerates. Nerve conduction speeds stay above 45 meters per second, but the signals are weaker because fewer nerve fibers are functioning. There’s also an intermediate form (DI-CMT) with conduction speeds that fall between 35 and 45 meters per second. Within these broad categories, dozens of specific genetic subtypes have been identified, each linked to mutations in different genes.
How CMT Is Inherited
CMT is a genetic condition, and the inheritance pattern depends on which gene is involved. The most common forms follow an autosomal dominant pattern, meaning you only need one copy of the altered gene (from one parent) to develop the disease. If a parent has autosomal dominant CMT, each child has a 50% chance of inheriting it. Other forms are autosomal recessive, requiring a mutated gene from both parents, and some are X-linked, carried on the X chromosome.
Getting a Diagnosis
Diagnosis typically starts with a neurological exam looking for the characteristic signs: weakness in the feet and ankles, reduced or absent reflexes, high arches, and sensory loss in a “stocking-glove” pattern. A detailed family history is important because CMT runs in families, though spontaneous new mutations do occur.
Nerve conduction studies are a key next step. By measuring how fast electrical signals travel through your nerves, doctors can distinguish between demyelinating and axonal forms and rule out other conditions. Certain muscle diseases that cause distal weakness can mimic CMT, but nerve conduction studies will be normal in those cases.
Genetic testing confirms the specific type. The recommended first step is testing for a PMP22 duplication, since it causes about 50% of all CMT. If that comes back negative, a multigene panel covering the eight most commonly involved genes is the next move. If those are also negative, broader genomic testing like exome sequencing can sometimes identify rarer mutations. Knowing your exact genetic subtype matters for family planning, understanding your prognosis, and eventually for eligibility in clinical trials.
Managing CMT Day to Day
There is no cure for CMT, but several strategies can meaningfully improve function and quality of life. The mainstay is physical therapy. Individualized exercise programs focused on strength and endurance training have been shown to improve muscle strength in both the upper and lower limbs and help people perform everyday activities more efficiently. The targeted muscles vary by person but often include the hip flexors, thigh muscles, and arm muscles, not just the obviously affected lower legs. Strengthening muscles higher up the chain helps compensate for what’s been lost distally.
Ankle-foot orthoses (AFOs) are one of the most practical tools for managing foot drop and instability. Several types exist, ranging from lightweight elastic braces to rigid plastic designs. Plastic AFOs tend to improve both posture and walking control, while elastic versions primarily help with the dynamic aspects of walking. Simpler devices like the “Footup splint,” which uses an elastic strap attached to a shoe, can prevent the foot from dropping during the swing phase of a step and reduce tripping. Many people with CMT rely on some form of bracing to maintain safe, independent mobility.
When Surgery Becomes an Option
For foot deformities that progress beyond what bracing can manage, orthopedic surgery can restore a more functional foot shape. The approach depends on how rigid the deformity has become. Mild, flexible deformities are often treated with soft tissue procedures: releasing the tight plantar fascia on the sole of the foot, transferring tendons to rebalance pull on the foot, or lengthening tight tendons.
More significant or rigid deformities typically require bone work. The most commonly performed procedures include calcaneal osteotomy (reshaping the heel bone) and first metatarsal osteotomy (correcting the bone behind the big toe), often combined with tendon transfers and plantar fascia release. For severe cases with joint degeneration, fusion of multiple joints in the hindfoot may be necessary. These surgeries aren’t about curing CMT; they’re about creating a foot that fits in a shoe, bears weight more evenly, and works better with a brace.
Living With CMT Long Term
CMT progresses slowly, and most people continue walking throughout their lives, though many come to rely on braces, orthotics, or other assistive devices over time. The disease rarely affects the muscles involved in breathing or other vital functions, and life expectancy is normal for the vast majority of people with CMT.
The practical challenges tend to center on foot and ankle problems, balance, hand dexterity, and fatigue. Adapting your environment, staying consistent with exercise, and working with an orthopedic specialist or physiatrist who understands CMT can make a significant difference in maintaining independence. A combination drug therapy called PXT3003, which targets CMT1A specifically, is currently in a Phase 3 clinical trial measuring its effect on disability and walking speed over 15 months. If successful, it would be the first approved medication for CMT, though results are still pending.