How the periphery nerves work

In order to understand the causes of Charcot-Marie-Tooth disease (CMT) it is useful to first understand how the periphery nerves work.

A periphery nerve is much like an electrical cable which is made of two parts - the axon and the myelin sheath.

* The axon - is like the wiring in an electrical cable. It is the part of the nerve that transmits the electrical information between the brain and your limbs.
* The myelin sheath - acts like the insulation of an electrical cable. It is wrapped around the axon, protecting it, and it also ensures that the electrical signal does not get broken up.

Different types of CMT (see below) can damage both of these functions. In some types of CMT, faulty genes cause the myelin sheath to disintegrate. Without the protection of the myelin sheath, the axons become damaged and the muscles and senses no longer receive the proper messages from the brain. This leads to the symptoms of muscle weakness and numbness.

In other types of CMT, it is the axons which are directly affected. Due to faulty genes, the axons do not transmit the electrical signals at the proper strength, so that the muscles and senses are under-stimulated. Again, this leads to symptoms of muscle weakness and numbness.