⁃ All patients must agree to take part in the study and sign a consent form. A teenager (age 13-17 years) considering enrolling must agree to take part in the study and sign an assent form (depending on local ethics committee requirements).

⁃ Additional inclusion criteria are described below.

⁃ Patients must have at least one of the following:

• Patient has a documented PMP22 duplication. AND/OR

• Patient has a first or second degree relative (parent, child, sibling, half- sibling, aunt, uncle, grandparent, grandchild, niece, or nephew) with a documented PMP22 duplication AND a clear link between that family member and the affected patient AND a phenotype consistent with CMT1A.

⁃ i. A clear link is necessary for a second-degree relative. For example, if a grandparent is affected and has a PMP22 duplication, and the parent does not have any signs, symptoms, or electrophysiology consistent with CMT1A, there is no clear link.

⁃ ii. In cases where clear links are not available, genetic testing is required for the patient or the first degree family member who is not clearly affected.

⁃ a. Patient has demonstrated neuropathy on nerve conduction studies or clinically diagnosed genetic neuropathy, in the opinion of the investigator or genetic counsellor.

• Person is a family member of a CMT patient who is enrolled in the CMT Exome Project.

• AND one of the following:

• Person does not have a peripheral neuropathy, in the opinion of the investigator or genetic counsellor.

• OR

• Person is suspected to have a peripheral neuropathy, but has not been examined at an INC site.