Charcot-Marie-Tooth is a form of Muscular Dystrophy. This disease is inherited and can be passed down for generations. CMT is primarily a disease of the nerves, where the myelin on the nerves does not stay intact and the messages from the brain to the muscles through the nerves are not carried properly. It differs from MD, because people who have CMT are born with normal muscles. The muscles dystrophy because those nerves cannot send the messages through. So the muscles don't move and they atrophy.
There are two diferent forms of CMT. One is the hypertrophic type, in which the small muscles of the hand are more affected and sensory changes are more pronounced than in the other type. It is also characterised by enlarged nerves and by degeneration of the sheath of myelin that insulates many of the body's nerve fibres. Neuronal form is the other, and affects the lower limb functions more, and there is greater loss of muscle bulk below the knee. There is also a greater chance of more severe weakness in the ankles and feet than in the hypertrophic form.
Both forms of CMT are hereditary. That is the only way you can get the disease.