[Studies of electromyography and genetics in children with Charcot-Marie-Tooth disease type 1]

To study the electromyographic and genetic characteristics in children with Charcot-Marie-Tooth disease type 1 (CMT1).

Routine electromyography and nerve conduction were performed in 24 children with CMT1. Polymerase chain reaction (PCR) combined with restriction enzyme digestion was used to detect gene duplication on chromosome 17p11.2-12. Ten healthy children served as the control group.

The peripheral nerve conduction velocity slowed or disappeared in all of the 24 patients (100%). The lesions of the sensory nerves were more severe than the motor nerves, and the lesions of the lower limbs were more severe than the upper limbs. Of 72 muscles detected, 40 (56%) showed neurogenic lesions. The older the patients, the more severe the muscle lesions. Specific junction fragments (1760 bp) were identified in 13 (54%) out of 24 patients, but were not identified in the healthy controls.

The electromyographic changes are characterized by peripheral nerve conduction velocities slowing and neurogenic lesions of muscles in children with CMT1. The PCR combined with restriction enzyme digestion may be a simple and accurate method for gene diagnosis of CMT1.