Charcot-Marie-Tooth disease (Hereditary Motor and Sensory Neuropathy) sometimes begins during childhood and can lead to learning and/or orthopedic disabilities. Due to the genetic and clinical heterogeneity of the disease, the diagnosis is based on a familial study of clinical, electromyographic and pathological abnormalities. Two major types of Charcot-Marie-Tooth disease have been described. Type 1 is characterized by a decrease in nerve conduction velocities and by a peripheral nerve hypertrophy due to myelinic alterations, while type 2 is the consequence of axonal alterations. Although type 1 and type 2 patients share similar clinical symptoms, type 2 patients have normal nerve conduction velocities and histological signs of axonal damage. Several genes involved in this disease have been recently located, and, in certain cases, an individual and direct diagnosis is available if the familial abnormality is related to chromosome 17.
