Charcot-Marie-Tooth Disease (CMT)

Causes/Inheritance

Causes of Charcot-Marie-Tooth disease (CMT)

peripheral nerve fibers

Peripheral nerves control movement by relaying impulses from the spinal cord (not shown) to the muscles (shown in the forearm). They also convey sensation and help with balance and awareness of the body’s position.

Diagnosis

A combination of lower leg weakness and foot deformities is a red flag for Charcot-Marie-Tooth disease (CMT) but isn’t sufficient for diagnosis. When a patient has those symptoms, a neurologist will usually start with a physical exam to look for further signs of distal weakness and sensory loss.

As a test for leg weakness, a neurologist might ask patients to walk on their heels or move part of their leg against an opposing force.

Signs and Symptoms

Partly because there are different types of Charcot-Marie-Tooth disease (CMT), the exact symptoms vary greatly from person to person. This section presents a general picture of CMT signs and symptoms.

This section covers:

Congenital Hypomyelinating Neuropathy (CHN)

What is Congenital Hypomyelinating Neuropathy (CHN)?

CHN is a subtype of Charcot-Marie-Tooth disease (CMT), a genetic, neurological disorder that causes damage to the peripheral nerves — tracts of nerve cell fibers that connect the brain and spinal cord to muscles and sensory organs.

Dejerine-Sottas disease

What is Dejerine-Sottas disease?

Dejerene-Sottas (DS) is a subtype of Charcot-Marie-Tooth disease (CMT), a genetic, neurological disorder that causes damage to the peripheral nerves — tracts of nerve cell fibers that connect the brain and spinal cord to muscles and sensory organs. DS is named for Joseph Dejerine and Jules Sottas, French neurologists who first described the disorder in 1893.

CMT4

What is Charcot-Marie-Tooth disease type 4 (CMT4)?

CMT4 is a subtype of CMT, a genetic, neurological disorder that causes damage to the peripheral nerves — tracts of nerve cell fibers that connect the brain and spinal cord to muscles and sensory organs.

CMTX

What is Charcot-Marie-Tooth disease type X (CMTX)?

CMTX is a subtype of CMT, a genetic, neurological disorder that causes damage to the peripheral nerves — tracts of nerve cell fibers that connect the brain and spinal cord to muscles and sensory organs.

CMT1-CMT2

What are Charcot-Marie-Tooth disease type 1 (CMT1) and type 2 (CMT2)?

These are the two most common forms of CMT, a genetic, neurological disorder that causes damage to the peripheral nerves — tracts of nerve cell fibers that connect the brain and spinal cord to muscles and sensory organs.

A subtype of CMT1, called CMT1A (caused by a defect in the PMP22 gene on chromosome 17) accounts for around 60 percent of all CMT cases.

Types of CMT

For axons and Schwann cells, communication is the key to a healthy relationship. Axons send chemical messages that attract Schwann cells and encourage myelin formation, and Schwann cells appear to send messages that nourish and protect axons. The various genetic defects that cause CMT often disrupt these interactions.

The many different types of Charcot-Marie-Tooth (CMT) are distinguished by age of onset, inheritance pattern, severity, and whether they're linked to defects in axon or myelin.

Overview

What is Charcot-Marie-Tooth disease (CMT)?

Illustration of systems affected by CMT
CMT causes degeneration of the peripheral nerves, leading to muscle weakness in the body’s extremities.

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