Charcot-Marie-Tooth disease type 1F

What it is

From: Orphanet

Charcot-Marie-Tooth disease type 1F (CMT1F) is a form of CMT1, with a variable clinical presentation that can range from severe impairment with onset in childhood to mild impairment appearing during adulthood. CMT1F is characterized by a progressive peripheral motor and sensory neuropathy with distal paresis in the lower limbs that varies from mild weakness to complete paralysis of the distal muscle groups, absent tendon reflexes and reduced nerve conduction. CMT1F represents the ''demyelinating'' form of CMT2E and is caused by mutations in the NEFL gene (8p21.2).

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Decreased nerve conduction velocity · Very frequent (99-80%)

A reduction in the speed at which electrical signals propagate along the axon of a neuron.

Demyelinating motor neuropathy · Very frequent (99-80%)

Demyelination of peripheral motor nerves.

Demyelinating sensory neuropathy · Very frequent (99-80%)

Demyelination of peripheral sensory nerves.

Distal muscle weakness · Very frequent (99-80%)

Reduced strength of the musculature of the distal extremities.

Skeletal muscle atrophy · Very frequent (99-80%)

The presence of skeletal muscular atrophy (which is also known as amyotrophy).

Somatic sensory dysfunction · Very frequent (99-80%)

An abnormality of the primary sensation that is mediated by peripheral nerves (pain, temperature, touch, vibration, joint position). The word hypoesthesia (or hypesthesia) refers to a reduction in cutaneous sensation to a specific type of testing.

Sensorimotor neuropathy · Very frequent (99-80%)

Abnormality of the hand · Frequent (79-30%)

An abnormality affecting one or both hands.

Absent brainstem auditory responses · Frequent (79-30%)

Lack of measurable response to stimulation of auditory evoked potentials.

Areflexia · Frequent (79-30%)

Absence of neurologic reflexes such as the knee-jerk reaction.

Cervical spinal cord atrophy · Frequent (79-30%)

Atrophy of the cervical segment of the spinal cord.

Decreased number of large peripheral myelinated nerve fibers · Frequent (79-30%)

A reduced number of large myelinated nerve fibers.

Distal lower limb amyotrophy · Frequent (79-30%)

Muscular atrophy of distal leg muscles.

Distal lower limb muscle weakness · Frequent (79-30%)

Reduced strength of the distal musculature of the legs.

Other findings in the same source

From: Orphanet

Additional reported features include Distal upper limb amyotrophy (Frequent (79-30%)); Foot dorsiflexor weakness (Frequent (79-30%)); Gait ataxia (Frequent (79-30%)); Hand muscle atrophy (Frequent (79-30%)); Hand muscle weakness (Frequent (79-30%)); Hand tremor (Frequent (79-30%)); Head tremor (Frequent (79-30%)); Impaired pain sensation (Frequent (79-30%)); Impaired proprioception (Frequent (79-30%)); Impaired vibratory sensation (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Childhood; Infancy

Inheritance in the source

From: Orphanet

Autosomal dominant

Frequency and the population described

From: Orphanet

Point prevalence: Unknown; Worldwide; Class only.

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal dominant pattern means that one altered copy of a relevant gene can be sufficient for the condition. Some affected people inherit the change; others have a new change without an affected parent. The precise finding, family history and condition determine what this means for relatives.

Which doctor should you see?

The suggested department for discussing Charcot-Marie-Tooth disease type 1F is Neurology, with a neurologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which nervous-system findings help explain the symptoms?
• Would an assessment of walking, communication or daily function be helpful?
• Are rehabilitation or other specialist services relevant?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Charcot-Marie-Tooth disease type 1F. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.