Charcot-Marie-Tooth disease type 1 is a genetic nerve condition that weakens the muscles in the feet and legs first. People with Charcot-Marie-Tooth disease type 1 often notice foot drop, ankle sprains, high arches, and numbness or tingling. Signs usually begin in childhood or the teen years and progress slowly over a lifetime. Most people live a normal lifespan, but daily activities can be affected by balance and hand strength changes. Treatment focuses on physical and occupational therapy, ankle-foot braces, pain control, and sometimes surgery to support mobility and hand function.
Overview
Charcot-marie-tooth disease type 1Symptoms
Charcot-Marie-Tooth disease type 1 causes slowly progressive weakness in the feet and lower legs, leading to tripping, foot drop, high arches, and balance problems. Early symptoms of Charcot-Marie-Tooth disease type 1 include numbness, tingling, cramps, and reduced ankle reflexes.
Outlook and prognosis
Most people with Charcot-Marie-Tooth disease type 1 have a slow, gradual change in strength and sensation, often over decades. Many stay active, use braces or therapy to support mobility, and adapt well at work and home. Life expectancy is typically normal.
Causes and risk factors
Charcot‑Marie‑Tooth disease type 1 usually stems from inherited changes in nerve‑support genes, most often a PMP22 duplication. It’s typically autosomal dominant, though new mutations occur. Family history raises risk; diabetes, alcohol misuse, certain nerve‑toxic medicines, and overuse may worsen severity.
Genetic influences
Genetics are central in Charcot-Marie-Tooth disease type 1; inherited variants disrupt myelin, slowing nerve signals. Most cases follow autosomal dominant patterns, though recessive and de novo changes occur. Genetic testing can confirm subtype, guide prognosis, and support family planning.
Diagnosis
Doctors look for characteristic clinical features and a family pattern. Nerve conduction studies showing demyelination support the diagnosis of Charcot‑Marie‑Tooth disease type 1. Genetic testing then confirms the genetic diagnosis of Charcot‑Marie‑Tooth disease type 1 and identifies the subtype.
Treatment and drugs
Treatment for Charcot‑Marie‑Tooth disease type 1 focuses on keeping you moving and safe. Many benefit from physical and occupational therapy, ankle‑foot orthoses, custom footwear, and fall‑prevention. Pain control, neuropathic pain medicines, and, when needed, orthopedic surgery are considered.
Symptoms
Charcot-Marie-Tooth disease type 1 often shows up first in the lower legs and feet, making walking, running, or keeping balance harder than before. If you’re watching for early features of Charcot-Marie-Tooth disease type 1, the first changes often involve the feet and ankles. Features vary from person to person and can change over time. Many notice high arches, weaker ankles, or trips and ankle sprains, with hand changes arriving later.
Weakness lifting the front of the foot can cause tripping or a high-stepping walk. In Charcot-Marie-Tooth disease type 1, this can be one of the earliest walking changes.
Looser, weaker ankles can lead to frequent sprains and a wobbly feeling. Supportive shoes or braces may reduce falls and pain.
High arches and curled toes can make shoes uncomfortable and cause pressure spots. In Charcot-Marie-Tooth disease type 1, these foot shapes often appear in childhood or the teen years.
Muscles below the knees can shrink over time, making the calves look thinner. This can make it harder to run, jump, or stand on your heels.
How people usually first notice Charcot-marie-tooth disease type 1?
Many people first notice Charcot‑Marie‑Tooth disease type 1 (CMT1) in childhood or the teen years when tripping, ankle rolling, or unusually frequent falls start to stand out, often along with difficulty running or keeping up in gym class. Families and clinicians may spot high arches or hammertoes, thinner lower legs that look “inverted bottle” shaped, or ankle weakness that leads to foot drop; these early features often prompt a nerve exam and, later, genetic testing. If you’re wondering about the first signs of Charcot‑Marie‑Tooth disease type 1, they’re usually subtle changes in balance, gait, and foot shape that gradually become more noticeable over time.
Types of Charcot-marie-tooth disease type 1
Charcot-Marie-Tooth disease type 1 (CMT1) has several well-recognized genetic subtypes, and these variants can shape when symptoms begin and how fast they progress. People may notice different sets of symptoms depending on their situation. All CMT1 variants affect the insulating sheath around nerves (myelin), which slows signals to the muscles and leads to weakness and sensory changes in the feet and hands. Knowing the types of CMT1 can help explain patterns like early foot drop, walking changes, or how strongly reflexes are reduced.
CMT1A (PMP22)
This is the most common type and often starts in childhood or the teen years. It typically causes slowly progressive foot weakness, ankle sprains, high arches, and reduced reflexes.
CMT1B (MPZ)
Symptoms can begin in infancy, childhood, or adulthood, with wide variability. Some have earlier walking delays and more sensory loss, while others notice milder hand and foot weakness later on.
CMT1C (LITAF)
Usually starts in childhood to early adulthood with mild to moderate weakness. People often have balance issues and decreased sensation in the feet, and symptoms progress slowly.
CMT1D (EGR2)
Tends to be less common and more variable in severity. Some experience early, more noticeable weakness and sensory changes, while others have a milder course.
CMT1E (PMP22 point)
Caused by specific PMP22 mutations rather than a duplication. It can range from early, more severe weakness and sensory loss to a milder, later-onset picture.
CMT1F (NEFL)
May begin in childhood or young adulthood with gait changes and foot drop. Hand weakness and sensory loss can develop over time, and nerve tests often show markedly slowed signals.
X-linked CMT (GJB1/Cx32)
Though classically grouped as CMTX1, many families compare it alongside CMT1 because myelin is affected. Males often have earlier, more pronounced weakness and sensory loss, while females can be milder with later onset.
What genetics can tell you about symptoms
Certain CMT1 gene changes, like PMP22 duplication, often cause slowly progressive weakness and numbness starting in the feet, high arches, and reduced reflexes. Other variants, such as MPZ or LITAF mutations, can bring earlier walking delays, more severe balance problems, or variable pain.
Causes and risk factors
Charcot‑Marie‑Tooth disease type 1 is caused by a change in a nerve‑supporting gene, most often an extra copy of a gene called PMP22. Genes set the stage, but environment and lifestyle often decide how the story unfolds. The main risk is having a parent with the gene change, and a new change can also appear for the first time. Risks that can worsen symptoms include nerve‑toxic medicines like vincristine, heavy alcohol use, and poorly controlled diabetes. Healthy habits do not prevent CMT1, but staying active, keeping a healthy weight, and avoiding nerve‑toxic drugs can lower complications such as falls and pain.
Environmental and biological risk factors
Environmental and biological risk factors for Charcot-Marie-Tooth disease type 1 are not well defined. For most families, the condition appears regardless of parental age, pregnancy health, or typical exposures. Researchers are still exploring how outside influences interact with our inner biology. Here’s what current evidence suggests.
No specific chemicals, heavy metals, or typical environmental radiation have been shown to raise the chance of Charcot-Marie-Tooth disease type 1. Common home or workplace exposures have not been linked.
Research has not found a consistent age-related increase in risk. Charcot-Marie-Tooth disease type 1 can occur at any maternal or paternal age.
Common pregnancy conditions like diabetes or thyroid disease are not known to cause this condition. They matter for overall pregnancy health but have not been tied to Charcot-Marie-Tooth disease type 1.
Usual viral or bacterial infections have not been linked to higher risk. Severe infections can affect fetal health, but current data do not connect them to this condition.
Genetic risk factors
Charcot-Marie-Tooth disease type 1 (CMT1) is most often caused by inherited changes in genes that help build and maintain the myelin coating around peripheral nerves. The most common change is an extra copy of the PMP22 gene; other genes such as MPZ, LITAF, EGR2, NEFL, and certain PMP22 point changes can also lead to CMT1. Carrying a genetic change doesn’t guarantee the condition will appear. Most CMT1 types are passed in an autosomal dominant way, so each child of an affected parent has a 50% chance to inherit the gene change.
PMP22 duplication: An extra copy of the PMP22 gene (CMT1A) is the leading genetic cause of CMT1. The extra gene dose disrupts myelin production, slowing nerve signaling. Severity can vary within the same family.
MPZ changes: Changes in the MPZ gene (CMT1B) are the second most common cause. They affect a key myelin protein and can present from childhood to adulthood. Severity can differ widely.
PMP22 mutations: Single-letter changes in PMP22 (CMT1E) are less common than the duplication. They can cause demyelination and may be linked to earlier or more noticeable nerve involvement.
LITAF changes: Variants in LITAF (CMT1C) are a rare cause of CMT1. They alter how myelin is processed in peripheral nerves.
EGR2 changes: Rare changes in EGR2 (CMT1D) can disrupt regulation of myelin genes. Some families show earlier onset, while others have a milder course.
NEFL changes: Changes in NEFL (sometimes called CMT1F) can cause a demyelinating form in some families. Effects vary, and some variants show a mixed pattern of nerve changes.
Autosomal dominant: Most CMT1 subtypes follow an autosomal dominant pattern. Each child of an affected parent has a 50% (1 in 2) chance to inherit the gene change. Severity and age at onset can differ even among relatives.
Family history: Having a parent or close relative with CMT1 increases the likelihood of the same genetic change. Genetic testing for Charcot-Marie-Tooth disease type 1 can confirm the gene involved and clarify relatives’ risks. Building a family tree helps identify who may benefit from testing.
De novo variants: CMT1 can arise from a new genetic change in a child with no prior family history. When this happens, recurrence risk for future siblings is usually low. Rarely, a small portion of a parent’s egg or sperm cells carries the change (mosaicism), which can slightly increase recurrence risk.
Genetic modifiers: Other genes may modify how strongly a CMT1 gene change shows up. This helps explain why some family members have milder or later-onset features than others.
Lifestyle risk factors
Lifestyle habits do not cause Charcot-marie-tooth disease type 1, but they can shape symptom burden, progression of weakness, and risk of complications like falls and foot injuries. Thoughtful choices about movement, footwear, alcohol and tobacco use, and nutrition can make daily function safer and more comfortable. Below are lifestyle risk factors for Charcot-marie-tooth disease type 1 and practical ways they influence symptoms and complications.
Consistent low- to moderate-intensity aerobic activity and balance work can help maintain walking efficiency and reduce fall risk in CMT1. Overexertion that causes prolonged weakness or severe next-day fatigue suggests you should pace and rest.
Repetitive jumping, cutting, or contact sports can increase ankle sprains and foot fractures in CMT1. Lower-impact options like cycling, swimming, or elliptical reduce joint stress while maintaining conditioning.
Targeted strengthening of dorsiflexors, hip abductors, and core can improve foot clearance and stability in CMT1. Heavy eccentric loads that flare muscle fatigue may need modification with lighter resistance and more rest.
Supportive shoes with firm heel counters and wide toe boxes improve stability and reduce pressure points in CMT1. High heels, flip-flops, or worn-out soles increase tripping and ulcer risk.
Risk prevention
Charcot-Marie-Tooth disease type 1 (CMT1) can’t be prevented, but you can lower the chance of falls, injuries, and joint problems, and maintain function longer. Recognizing early symptoms of Charcot-Marie-Tooth disease type 1—like frequent ankle rolling, tripping, or foot weakness—and acting early can help preserve strength and balance. Prevention works best when combined with regular check-ups. The aim is to protect nerves and muscles, support safe movement, and catch complications early.
See a neuromuscular or rehabilitation clinic regularly to track strength, sensation, and gait in CMT1. Early referrals for therapy or orthopedics can prevent small issues from becoming major problems.
Low‑impact activity like swimming, cycling, or walking builds stamina without overstraining weak muscles in Charcot-Marie-Tooth disease type 1. A physical therapist can tailor exercises to protect joints and improve balance.
Daily calf, hamstring, and ankle stretches help keep joints flexible in CMT1. This may reduce cramps and delay tight tendons and contractures.
Braces (AFOs) and custom insoles can steady weak ankles and lift the forefoot in Charcot-Marie-Tooth disease type 1. This lowers tripping risk and protects joints from repeated sprains.
Transmission
Charcot-Marie-Tooth disease type 1 is not contagious—you can’t catch it from someone or spread it through everyday contact or bodily fluids. The genetic transmission of Charcot-Marie-Tooth disease type 1 is usually autosomal dominant, meaning a change in one copy of a gene from one parent is enough to cause the condition. If a parent has CMT1, each child has a 1 in 2 (50%) chance of inheriting it. Sometimes it appears in a family for the first time because of a new genetic change, and that person can then pass it on to their children.
When to test your genes
Consider genetic testing if you have progressive foot weakness, high arches, frequent ankle sprains, or a family history of Charcot-Marie-Tooth disease type 1. Testing helps confirm the subtype, guides prognosis, supports bracing and therapy choices, and informs reproductive planning. It’s also reasonable before starting new nerve-affecting medications or when symptoms begin in childhood.
Diagnosis
For many, the first step comes when everyday activities start feeling harder, like tripping more often or noticing ankle weakness. Doctors focus on the diagnosis of Charcot-Marie-Tooth disease type 1 by combining what they see in the exam with nerve tests and, when appropriate, genetic tests. Early and accurate diagnosis can help you plan ahead with confidence. Many people feel relief just knowing what’s really going on.
Providers look for slowly progressive foot weakness, high arches, hammertoes, and reduced sensation in the feet and hands. These features tend to be fairly symmetric and begin in childhood or the teen years, though timing varies. Over time, calf thinning and ankle instability may become noticeable.
Doctors check strength, reflexes, balance, and different types of sensation. Reduced or absent ankle reflexes and weakness in the feet and lower legs are common findings. A careful exam helps distinguish hereditary neuropathy from other nerve problems.
Small patches on the skin deliver mild electrical signals to measure how fast nerves conduct. In CMT1, speeds are uniformly slow, which points to a problem with the nerve’s insulating layer. This pattern helps separate CMT1 from acquired demyelinating neuropathies.
A fine needle measures electrical activity in muscles at rest and with movement. EMG can show changes that support a long-standing nerve problem and complements nerve conduction studies. Together, these tests strengthen the case for a hereditary neuropathy.
Stages of Charcot-marie-tooth disease type 1
Charcot-marie-tooth disease type 1 does not have defined progression stages. It usually changes slowly over many years and varies widely from person to person and between subtypes, so doctors don’t group it into standard stages. Different tests may be suggested to help confirm the diagnosis and track changes over time, including a physical exam, nerve studies, and sometimes genetic testing. For many, early symptoms of Charcot-marie-tooth disease type 1 include ankle weakness, frequent tripping, or high-arched feet, and clinicians monitor these features over time rather than assign a stage.
Outlook and prognosis
Many people ask, “What does this mean for my future?”, especially after a new diagnosis of Charcot‑Marie‑Tooth disease type 1 (CMT1). In general, CMT1 progresses slowly over years, not weeks, and most people maintain independence in daily activities for a long time. Early symptoms of Charcot‑Marie‑Tooth disease type 1 often include tripping on uneven ground, ankle rolling, or trouble with buttons; these typically evolve into foot drop, hand weakness, and balance problems that can limit running or climbing stairs but still allow for walking. The outlook is not the same for everyone, but most people with CMT1 have a normal life span, and CMT1 itself is not considered life‑limiting.
Looking at the long-term picture can be helpful. Many living with CMT1 notice symptoms worsen during growth spurts or mid‑life, then level off for periods. In medical terms, the long-term outlook is often shaped by both genetics and lifestyle. For example, specific gene changes can be linked to earlier onset or more hand involvement, while consistent physical therapy, ankle‑foot orthoses, and fall‑prevention strategies can preserve mobility and reduce complications.
Even though it can feel overwhelming, severe complications like breathing or swallowing problems are uncommon in CMT1; when they do occur, they’re usually mild and manageable. Pain, cramps, and fatigue can flare but are usually controllable with a tailored plan, and with ongoing care, many people maintain work, family roles, and hobbies. Understanding the prognosis can guide planning and help you pace activities, choose supportive footwear, and time rest so you can do more of what matters day to day. Talk with your doctor about what your personal outlook might look like, including how your specific subtype, current strength and balance, and any genetic results could shape the years ahead.
Long-term effects
Charcot-Marie-Tooth disease type 1 tends to progress slowly over many years, with most people maintaining a typical life span. Long-term effects vary widely, and changes often unfold gradually from the feet upward. Early symptoms of Charcot-Marie-Tooth disease type 1 often start in the ankles and arches, then extend to the lower legs and hands over time. Many notice a steady shift in strength, balance, and sensation rather than sudden changes.
Weakness usually begins in the feet and lower legs and can slowly progress to the hands. This often leads to foot drop and difficulty climbing stairs.
Over time, the small muscles in the calves, feet, and hands can shrink. This can make ankles look thinner and reduce grip strength.
High arches and hammertoes commonly develop and tend to persist. These changes can make shoes uncomfortable and walking less stable.
Walking may become unsteady with tripping on uneven ground. Falls can occur, especially in the dark or when tired.
How is it to live with Charcot-marie-tooth disease type 1?
Living with Charcot‑Marie‑Tooth disease type 1 often means adapting to slowly changing strength and balance over years, planning around fatigue, and using supports like ankle‑foot orthoses or hand grips to stay mobile and independent. Daily tasks—buttoning clothes, walking on uneven ground, or keeping up with a busy day—can take extra time and energy, but pacing, physical therapy, and smart tools help many keep doing what matters. For family and friends, it may mean offering practical help, being flexible with plans, and understanding that symptoms can fluctuate from day to day. With good routines, regular care, and honest communication, many build a steady rhythm that protects function and preserves quality of life.
Treatment and drugs
Treatment for Charcot-Marie-Tooth disease type 1 focuses on easing symptoms, protecting joint function, and maintaining independence over time. Physical and occupational therapy are the backbone: targeted exercises help keep muscles strong and flexible, braces or splints support weak ankles and wrists, and custom shoes or inserts improve balance and reduce falls. Doctors sometimes recommend a combination of lifestyle changes and drugs, such as pain relievers for nerve pain or muscle cramps, along with safety tweaks at home to prevent injuries. Surgery may be considered for severe foot deformities or tendon imbalance when braces aren’t enough, and regular follow-up helps adjust supports as needs change. Supportive care can make a real difference in how you feel day to day.
Non-drug treatment
Living with weak ankles, hand cramps, or unsteady steps can make everyday tasks feel harder. Supportive therapies can build strength, protect joints, and help you move more safely at home and outdoors. For Charcot-marie-tooth disease type 1, care often centers on physical and occupational therapy, bracing, foot care, and practical tools that match your needs over time. Plans are tailored and may change as early symptoms of Charcot-marie-tooth disease type 1 shift or new goals emerge.
Targeted exercises help maintain strength, stretch tight muscles, and protect joints. A therapist can design safe routines to improve walking and reduce falls. Programs are adjusted as needs change.
Training focuses on everyday tasks like buttoning shirts, opening jars, or typing. Therapists suggest techniques and tools to protect hands and save energy. This supports independence at home, work, and school.
Lightweight braces help lift the toes, steady weak ankles, and smooth out your stride. In Charcot-marie-tooth disease type 1, they can reduce tripping and fatigue. A specialist ensures proper fit and comfort.
Supportive shoes and custom insoles redistribute pressure and improve stability. They can prevent calluses and reduce foot pain from high arches or hammertoes. A podiatrist can guide choices as feet change.
Your genes may have an impact on how drugs work for you
In Charcot–Marie–Tooth disease type 1, genes can alter how your body absorbs and clears medications for pain, cramps, or neuropathic symptoms, changing dose needs and side‑effect risk. Pharmacogenetic testing and careful monitoring help tailor safer, more effective treatment.
Pharmacological treatments
There’s no single medicine that can cure Charcot-Marie-Tooth disease type 1, but several drugs can ease specific symptoms and improve day-to-day comfort. Drugs that target symptoms directly are called symptomatic treatments. These focus on nerve pain, muscle cramps, tremor, and sleep issues that may follow early symptoms of Charcot-Marie-Tooth disease type 1. Most treatments are tailored, so doses and choices are adjusted over time based on benefit and side effects.
Duloxetine, pregabalin, and gabapentin can reduce burning, shooting, or electric-like nerve pain in CMT1. Tricyclics such as amitriptyline or nortriptyline are alternatives, especially for nighttime pain.
Lidocaine 5% patches or gel can numb a painful area without affecting the whole body. High‑strength capsaicin 8% patch may help stubborn focal pain when applied in a clinic.
Acetaminophen (paracetamol) or NSAIDs like ibuprofen or naproxen can help soreness from overuse, joint strain, or injuries. These do not treat nerve pain directly but can be useful on busy or therapy-heavy days.
Mexiletine may ease frequent, painful cramps in some people with CMT1, but it’s off‑label and needs heart rhythm monitoring. Baclofen or tizanidine can reduce muscle tightness or spasms, particularly at night.
Genetic influences
In most families, Charcot-Marie-Tooth disease type 1 is inherited, usually from a parent who also has the condition. The most common cause is having an extra copy of a nerve‑supporting gene called PMP22, which disrupts the myelin insulation around nerves and slows signals to the feet and hands. This pattern means each child of an affected parent has a 50% (1 in 2) chance of inheriting the gene change; this is known medically as autosomal dominant. Even with the same gene change, people can have different ages of onset, nerve test results, and day‑to‑day impact. That’s why early symptoms of Charcot‑Marie‑Tooth disease type 1 can vary even within the same family—from frequent ankle sprains in school years to subtle foot weakness that isn’t noticed until adulthood. Sometimes there’s no family history because the gene change starts for the first time in the individual; genetic testing and counseling can clarify the cause and guide planning for relatives.
Is Charcot-marie-tooth disease type 1 genetic?
Genetics are central in Charcot-Marie-Tooth disease type 1; inherited variants disrupt myelin, slowing nerve signals. Most cases follow autosomal dominant patterns, though recessive and de novo changes occur. Genetic testing can confirm subtype, guide prognosis, and support family planning.
Pharmacogenetics—how genetics influence drug effects
For many living with Charcot–Marie–Tooth disease type 1 (CMT1), genetics can influence which treatments are safest and which are more likely to help with day‑to‑day symptoms like nerve pain and cramps. The most common form, CMT1A, is driven by extra activity of a nerve‑supporting gene called PMP22, and several research treatments are designed to gently turn that gene down—so your exact subtype can matter when targeted options become available. Doctors are also careful about medications to avoid in Charcot–Marie–Tooth disease type 1; drugs that can damage nerves, especially the chemotherapy medicine vincristine, are generally avoided when possible. For symptom control, common medicines for nerve pain—including certain antidepressants (like tricyclics), some opioids such as codeine or tramadol, and carbamazepine—can be affected by drug‑metabolism genes, changing how well they work and what side effects you feel. Genetic testing can sometimes identify how your body handles certain pain medicines or your risk of rare but serious reactions, guiding dose and choice. By contrast, gabapentin and pregabalin are not broken down by liver enzymes, so inherited differences in those enzymes usually matter less for these options. Genes are only part of the picture—your other health conditions, kidney and liver function, and the mix of medicines you take also shape what’s safest and most effective for you.
Interactions with other conditions
When Charcot-Marie-Tooth disease type 1 affects the feet and hands, having another condition that also harms nerves—like diabetes or heavy alcohol use—can intensify numbness, burning pain, and balance problems, and raise the risk of foot sores. Doctors call it a “comorbidity” when two conditions occur together. Early symptoms of Charcot-Marie-Tooth disease type 1 can even be mistaken for diabetic neuropathy when both are present, so careful evaluation matters. Carpal tunnel syndrome is more common in people with CMT1, and the chance is higher if you also live with diabetes or an underactive thyroid, which can add hand pain, tingling, or grip weakness. Certain cancer drugs that are tough on nerves—especially vincristine—may sharply worsen CMT1 symptoms, so make sure your oncology and neurology teams coordinate before treatment. Foot shape changes from CMT1 combined with diabetes or poor circulation can lead to slow‑healing ulcers and infections, making regular foot checks and protective footwear especially important.
How genes can cause diseases
Humans have more than 20,000 genes, each carrying out one or a few specific functions in the body. One gene instructs the body to digest lactose from milk, another tells the body how to build strong bones and another prevents the body's cells from beginning to multiply uncontrollably and developing into cancer. As all of these genes combined are the building instructions for our body, a defect in one of these genes can have severe health consequences.
Through decades of genetic research, we know the genetic code of any healthy/functional human gene. We have also identified that in certain positions on a gene, some individuals may have a different genetic letter from the one you have. We call these hotspots "Genetic Variations" or "Variants" in short. In many cases, studies have been able to show that having the genetic letter "G" in the position makes you healthy, but having the letter "A" in the same position disrupts the gene function and causes a disease. Genopedia allows you to view these variants in genes and summarizes all that we know from scientific research, which genetic letters (Genotype) have good or bad consequences on your health or on your traits.
History
Throughout history, people have described families in which several relatives developed weakness in the lower legs and ankles, tripped often, and later needed braces or high-top shoes to steady their steps. Community stories often described the condition as “the family with thin calves” or “those who walk on the edges of their feet,” long before tests could explain why.
First described in the medical literature as a pattern of slowly progressive, inherited nerve damage in the late 1800s, Charcot–Marie–Tooth disease type 1 (CMT1) was initially recognized through careful bedside observation. Doctors noted high arches, hammertoes, and reduced reflexes, along with numbness in the feet and hands. Early reports grouped many forms together, not yet separating CMT1 from other types that affect the nerve differently.
Over time, descriptions became more detailed. As electrical nerve testing emerged in the mid-20th century, clinicians could measure how fast signals traveled along the nerves. People with CMT1 showed slowed conduction, pointing to problems with the nerve’s insulating covering, known medically as myelin. This helped distinguish CMT1 from axonal forms, where the inner wiring of the nerve is primarily affected.
Advances in genetics in the late 20th century reshaped the story. Researchers discovered that a small extra copy (duplication) of a gene called PMP22 on chromosome 17 explains many cases of CMT1, now often labeled CMT1A. Soon after, changes in other myelin-related genes, including MPZ and LITAF, were linked to additional CMT1 subtypes. These findings confirmed what families had long noticed: inheritance patterns were consistent with a condition passed down in an autosomal dominant way in many lineages, while also making room for rare exceptions and new mutations.
With each decade, classification improved. What had once been a single umbrella term became a set of related diagnoses with shared features—gradual distal weakness and sensory loss—yet differing genetic causes and ages of onset. Genetic testing allowed more precise counseling, helped relatives understand their chances of inheriting CMT1, and guided supportive care. At the same time, clinicians recognized variability: some people develop symptoms in childhood, while others notice them in midlife; even within one family, the pace and pattern can differ.
In recent decades, knowledge has built on a long tradition of observation. Natural history studies have tracked how CMT1 changes over time, informing goals for physical therapy, ankle-foot orthoses, and fall prevention. Research continues into treatments aimed at the myelin problem at the root of CMT1, while patient registries and international collaborations map the condition more accurately across populations. Looking back helps explain why early symptoms of Charcot–Marie–Tooth disease type 1 were once hard to pin down—and why today’s care is more tailored than ever.