X-Linked Form of Charcot-Marie-Tooth Disease (CMT X)

The X-linked form of Charcot-Marie-Tooth disease (CMT1X) is the second most common form of hereditary motor and sensory neuropathy. The clinical phenotype is characterized by progressive muscle atrophy and weakness, areflexia, variable sensory abnormalities, and central nervous system manifestations. Neurophysiology shows intermediate slowing of conduction and distal axonal loss. Nerve biopsies show more prominent axonal degeneration than de- and remyelination. More than 400 different mutations in GJB1, the gene that encodes the gap junction (GJ) protein connexin 32 (Cx32), are known to cause CMT1X. An effective therapy remains to be developed.