Charcot-Marie-Tooth disease type 4A

What it is

From: Orphanet

A form of Charcot-Marie-Tooth disease type 4 characterized by early-onset (infancy to early childhood) of severe, rapidly progressing axonal, demyelinating, or intermediate sensorimotor neuropathy usually affecting first, and more severely, the distal lower extremities and later the proximal muscles and upper extremities. Nerve conduction velocities range from very slow to normal. Apart from the typical CMT phenotype (distal muscle weakness and atrophy, sensory loss, frequent pes cavus foot deformity), patients commonly present delayed motor development, vocal cord paresis, mild sensory loss, abolished deep tendon reflexes, and skeletal deformities.

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.

Abnormal foot morphology · Very frequent (99-80%)

An abnormality of the skeleton of foot.

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

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

Distal amyotrophy · Very frequent (99-80%)

Muscular atrophy affecting muscles in the distal portions of the extremities.

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

Reduced strength of the musculature of the distal extremities.

Distal sensory impairment · Very frequent (99-80%)

An abnormal reduction in sensation in the distal portions of the extremities.

EMG abnormality · Very frequent (99-80%)

Abnormal results of investigations using electromyography (EMG).

Pes cavus · Very frequent (99-80%)

An increase in height of the medial longitudinal arch of the foot that does not flatten on weight bearing (i.e., a distinctly hollow form of the sole of the foot when it is bearing weight).

Poor fine motor coordination · Very frequent (99-80%)

An abnormality of the ability (skills) to perform a precise movement of small muscles with the intent to perform a specific act. Fine motor skills are required to mediate movements of the wrists, hands, fingers, feet, and toes.

Poor gross motor coordination · Very frequent (99-80%)

An abnormality of the ability (skills) to perform a precise movement of large muscles with the intent to perform a specific act. Gross motor skills are required to mediate movements of the arms, legs, and other large body parts.

Areflexia · Frequent (79-30%)

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

Bilateral talipes equinovarus · Frequent (79-30%)

Bilateral clubfoot deformity.

Chronic axonal neuropathy · Frequent (79-30%)

An abnormality characterized by chronic impairment of the normal functioning of the axons.

Decreased Achilles reflex · Frequent (79-30%)

Decreased intensity of the Achilles reflex (also known as the ankle jerk reflex), which can be elicited by tapping the tendon is tapped while the foot is dorsiflexed.

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

A reduced number of large myelinated nerve fibers.

Other findings in the same source

From: Orphanet

Additional reported features include Hammertoe (Frequent (79-30%)); Hand muscle weakness (Frequent (79-30%)); Hoarse voice (Frequent (79-30%)); Hyporeflexia of upper limbs (Frequent (79-30%)); Impaired distal proprioception (Frequent (79-30%)); Impaired distal tactile sensation (Frequent (79-30%)); Impaired distal vibration sensation (Frequent (79-30%)); Impaired pain sensation (Frequent (79-30%)); Inability to walk (Frequent (79-30%)); Joint contracture of the hand (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Infancy; Neonatal

Inheritance in the source

From: Orphanet

Autosomal recessive

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing Charcot-Marie-Tooth disease type 4A 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 4A. 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.