ABSTRACT
Objective To study the clinical and electrophysiological features in Charcot-Marie-Tooth disease type 1A with gene duplication.Methods Clinical symptoms and signs were summarized in 22 patients from 21 unrelated families. Electromyography (EMG) as well as motor conduction velocities (MCV) and sensory conduction velocities (SCV) examinations were performed in all patients. Results Evidence of CMT was initially detected within the second decade in 18 patients. Nearly half of patients were sporadic cases. The typical clinical manifestations of CMT1A were weakness and atrophy in the distal limbs, weakness or absence of the tendon reflexes, talipes equinovarus and postural tremor the upper limb. Additionally, some special symptoms and signs were also observed occasionally, including brisk tendon reflexes, extensor plantar responses, scoliosis, foot ulcers and nystagmus. EMG revealed that 77.3% of the patients had fibrillation and positive sharp potentials. 81.8% of them had prolonged motor unit potential limit. Median MCV showed there was no significant difference between CMT1A patients and CMT1 patients without duplication (t=1.63, P＞0.05). Values of SCV and MCV for the lower limbs were not obtained in 20 patients and more than 2/3 of the patients respectively. Conclusions The clinical features of CMT1A included high frequent of sporadic cases, early onset in the second decade and various manifestations. The electrophysiological features were that the damages of nerves for the lower limbs were more severer than those in the upper limbs and the damages of the sensory nerves were more severer than those of the motor nerves. The phenotype was variable although the genotype was the same in CMT1A patients with PMP22 duplication.