Charcot Marie Tooth Disease (CMT) is a group of disorders that cause a peripheral neuropathy, impairing the long nerves that go to the feet and hands. Due to the problems with the peripheral nerves, people with CMT have muscle weakness and sensory loss that impairs their physical abilities. CMT affects approximately 1 in 2500 people and is caused my mutations in over 70 different genes. Models exist for many sub-types of CMT that have led to an increased understanding of the biological basis for these disorders. These advances have also made rational therapies for CMT a realistic possibility. However, clinical trials have been limited in CMT by a combination of lack of natural history data for many subtypes, a lack of outcome measures that can detect change in a short period for slowly progressive forms of CMT, and a lack of outcome measures for young children with CMT.