Charcot-Marie-Tooth disease, type 4G (CMT4G) is a demyelinating CMT peripheral sensorimotor polyneuropathy.
It has been identified in Bulgarian, Romanian, French, and Spanish Gypsies and is also referred to as hereditary motor and sensory neuropathy-Russe (HMSNR).
Onset occurs between 8 and 16 years of age with distal lower limb weakness, followed by distal upper limb involvement with a more variable age of onset of between 10 and 43 years. Sensory loss is also a prominent feature.
The disease-causing gene has not yet been identified but linkage analysis and recombination mapping have led to identification of a small interval on 10q23.2.
Motor nerve conduction velocities are moderately reduced and the threshold for electrical nerve stimulation is increased. Nerve biopsies reveal a loss of large myelinated fibers, reduced thickness of the myelin sheath and profuse regenerative activity.
CMT4G is transmitted in an autosomal recessive manner.
Last update: January 2009
- Dr Carmen ESPINÓS
- Pr Francesc PALAU