Charcot-Marie-Tooth (CMT) disease is a group of inherited disorders. It harms the nerves that control movement and feeling in the arms and legs. The disease gets worse over time.
CMT can be:
Type 1—This type affects the coating of the nerve called the myelin sheath, causing nerve impulses to travel more slowly. It usually happens to children and teens. It is the most common type of CMT.
Type 2—This type affects the part of the nerve called the axons. The speed of the nerves is normal, but the size or amount of impulses is less than normal. This type of CMT is less common. It happens after the teen years.
Type 3—Also called Dejerine-Sottas disease, this is a rare, severe form of CMT. It is sometimes thought to be a subtype of CMT Type 1.
Type 4—This is like Type 1, but often less severe. A person with it is less likely to pass it on to their children.
CMT is caused by changes in genes. In most people, the change is inherited. Some forms happen when only one copy of the abnormal gene is inherited. Other forms happen when both copies are inherited. Some other forms are inherited due to an abnormal x-linked chromosome.
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