Charcot-Marie-Tooth disease (CMT) is an inherited neurological disease characterized by a slowly progressive degeneration of the muscles in the foot, lower leg, hand, and forearm, and a mild loss of sensation in the limbs, fingers, and toes. The first sign of CMT is generally a high arched foot or gait disturbances.
Other symptoms of the disorder may include:
- Foot-bone abnormalities such as high arches and hammer toes
- Problems with hand function
- Problems with balance
- Occasional lower leg and forearm muscle cramping
- Loss of some normal reflexes
- Occasional partial sight and/or hearing loss
- Scoliosis – curvature of the spine (in some individuals)
Pregnancy has been known to exacerbate CMT, as well as extreme emotional stress.
This disease is one of the most common inherited neurological disorders, with 36 in 100,000 affected. People with CMT disease usually begin to experience symptoms in adolescence or early adulthood. CMT is presently incurable, however life expectancy is usually normal.
CMT disease can be divided into two classes, depending on where the dysfunction occurs in the peripheral nerves:
- In CMT type 1, the peripheral nerves’ axons – the part of the nerve cell that transmits electrical signals to the muscles – lose their protective outer coverings, their myelin sheaths. This disrupts the axons’ function.
- In CMT type 2, the axons’ responses are diminished due to a defect within the axons themselves. CMT type 2, the less common of the two classes, can be further separated into at least six subtypes, caused by defects in different genes.
The GARS gene is implicated in CMT type 2D, a form of CMT that primarily affects the hands and the forearms. CMT type 2D is inherited in an autosomal dominant fashion (you only need to get the abnormal gene from one parent in order for you to inherit the disease).
There is no cure for the disease, but there are treatment options, including physical therapy and bracing. A final decision a patient can make is to have surgery to stabilize their feet or correct progressive problems. These procedures include straightening and pinning the toes, lowering the arch, and sometimes, fusing the ankle joint to provide stability.