Demyelinating X-linked Charcot-Marie-Tooth disease: unusual electrophysiological findings

Muscle Nerve. 1999 Oct;22(10):1442-7. doi: 10.1002/(sici)1097-4598(199910)22:10<1442::aid-mus16>;2-6.


X-linked Charcot-Marie-Tooth disease (CMT-X) is caused by mutations of connexin-32 (Cx-32), which encodes a gap-junction protein. Whether the neuropathy is primarily demyelinative or axonal remains to be established. We report findings of prominent demyelination in a 71-year-old woman with late-onset disease. Electrophysiological studies revealed a nonuniform slowing of motor conduction velocities and dispersion of compound action potentials indicative of a demyelinating process which was confirmed by nerve biopsy. Such electrophysiological features are unusual in hereditary neuropathies and are more commonly found with acquired chronic demyelinating neuropathies. A systematic search confirmed the molecular genomic diagnosis of CMT-X, illustrating the value of such tests in sporadic cases. Severity of clinical symptoms and signs may vary with age and sex of the patient. The pathology of CMT-X in other reported cases has been variably interpreted as axonal, demyelinating, or showing both features. Our observations emphasize the demyelinative nature.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Aged
  • Charcot-Marie-Tooth Disease / genetics*
  • Charcot-Marie-Tooth Disease / pathology
  • Charcot-Marie-Tooth Disease / physiopathology*
  • Demyelinating Diseases / genetics*
  • Demyelinating Diseases / pathology
  • Demyelinating Diseases / physiopathology*
  • Electrophysiology
  • Female
  • Genetic Linkage*
  • Humans
  • Motor Neurons / physiology
  • Nerve Fibers, Myelinated / pathology
  • Neural Conduction
  • Time Factors
  • X Chromosome / genetics*