Charcot-Marie-Tooth disease (hereditary motor sensory neuropathy)

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What is Charcot-Marie-Tooth disease?

Charcot-Marie-Tooth (CMT) disease is a disease affecting the peripheral nerves.

The nervous system in the body can be divided into 2 categories: the central nervous system and the peripheral nervous system.

The peripheral nerves make up a vast network that transmits impulses from the brain and spinal cord (the central nervous system) to every other part of the body. Peripheral nerves also send sensory information back to the brain and spinal cord.

Peripheral neuropathies refer to a diverse group of diseases affecting the motor, sensory and autonomic nerves lying outside the central nervous system (i.e. the spinal cord and the brain). This can cause a wide variety of symptoms, such as weakness, numbness or sensitivity to touch.

Who gets Charcot-Marie-Tooth disease?

CMT disease is not uncommon. In fact, it affects 1 in 2500 of the population in the US, making it the commonest inherited nerve disease.

Below is the cases in different countries:

In Japan, prevalence is reported at 10.8 per 100,000 population

In Italy, prevalence is reported at 17.5 per 100,000 population

In Spain, prevalence is reported at 28.2 per 100,000 population

Some report as high as 40 cases in 100,000 population.

Predisposing Factors

CMT disease is a genetic disease, with the pattern of inheritance mainly autosomal dominant. This means that if a parent is affected, the children have 50% chance of developing the disease. It may also be autosomal recessive or X-linked recessive, both of which are rarer.

It affects all races and ethnic groups, and it has no gender predilection.

Progression

CMT disease comprises of a spectrum of disorders all caused by a specific mutation in one of several myelin genes. This eventually results in disturbances in myelin structure, maintenance, and formation.

Depending on the genetic defects, CMT can be divided into 7 types, classified as type 1 to type 7. CMT type 1 and type 2 are considered the most common of hereditary peripheral neuropathies.

Malfunctioning nerves can soon lead to disuse atrophy of the muscles gradually.

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