Abstract: Objective To explore the clinical features and diagnostic methods of Charcot-Marie-Tooth disease type 1 A (CMT 1 A). Methods The clinical manifestations, neuroelectrophysiology and genetic test results of a family with CMT 1 A were retrospectively analyzed. Results A 12 -year-old boy was admitted to hospital because of lower limbs weakness. Limbs hypotonia, level V of the proximal limbs myodynamia, level Ⅳof the distal muscle, symmetry atrophy of the muscle under the knee joint and the double distal upper limb muscles, symmetric limbs hypoesthesia, knee jerk and ankle reflex disappears, high arches feet. EMG examination indicated that the nerve conduction velocity slowed down. Gene detection results: Heterozygous duplication of exon 1 - 5 of PMP 22 gene was detected. All the patients showed high arch foot, leg muscle atrophy and limb weakness. EMG of the mother indicated decreased nerve conduction velocity, and gene test indicated heterogenous duplication of the EXon 1-5 of PMP22 gene. Conclusion CMT1A is related to the variation of PMP22 gene, which is autosomal dominant. The most common mutation is 1. 4 MB - 1. 5 MB repeated mutation. Clinical manifestations include progressive limb weakness, muscle atrophy, diminished or absent tendon reflexes, foot deformities, and paresthesia. Electromyography with MNCV less than 38 m/s and genetic test with PMP22 duplication can be diagnostic. Treatments including PXT3003 and phosphatidyl choline and phosphatidyl ethanolamine diet has being in clinical trials.

Key words: : hereditary peripheral neuropathy; Charcot-Marie-tooth disease; child