Charcot-Marie-Tooth disease (CMT) is a disorder of peripheral nerves. Peripheral nerves are those outside of the central nervous system (brain and spinal cord). They carry signals from the CNS to the muscles and other organs, and relay sensory information, such as pain and touch, from the rest of the body to the CNS.
In order to conduct information, a nerve cell (neuron) relays electrical signals from one end of the neuron to the other, down the long extension of the neuron called the axon. Myelin is a fatty layer that wraps around the axon in order to electrically insulate it, improving the efficiency of conduction.
CMT is actually a collection of a large group of disorders, caused by more than 30 different genes, and distinguished by age of onset, inheritance pattern, severity, and whether they're linked to defects in myelin or the axon.
The various forms of CMT1 are all due to defects in the myelin sheath surrounding the axon:
CMT2 is rarer than CMT1. The various forms of CMT2 all affect the axon itself, causing the axon to not function properly. Defects in transport, energy production and structure may result, depending on the gene involved.
Each of the many different forms of CMT is caused by a genetic mutation, and so various types of gene therapy have the potential to offer definitive treatment. Learning more about the specific consequences of each type of mutation may lead to disease-specific therapies to interrupt the disease process or compensate for its effects. Boosting the health of peripheral nerves is also potentially therapeutic. MDA researchers are pursuing all of these strategies.