G.P.86 X-linked Charcot–Marie–Tooth disease with c.22A>C missense mutation in the GJB1 gene in Koreans

Abstract

<h2>Abstract</h2> X-linked Charcot–Marie–Tooth disease (CMT1X) is caused by gap junction beta 1 (GJB1) gene mutations, which encodes the connexin 32. Connexin 32 is an integral transmembrane protein expressed in peripheral nerve myelin. The frequency of CMT1X varies among different ethnic groups. The frequency in Koreans is low compared with those in Europeans. Herein we present one CMT1X patient with missense mutation in the GJB1 gene. The 27-year-old male presented with complaints of slowly progressive weakness beginning in the distal leg muscles. He had walked with waddling gait ever since he had started walking at 2years of age. He felt a weak hand grip around 8years of age. He could not run and have numbness on toe tips after 18years old. The family history revealed a more severe disease phenotype in affected males compared with affected females. Physical examination showed pes cavus, wasting of muscles below knee, and intrinsic hand muscle atrophy. Neurological examination demonstrated predominantly distal muscle weakness in the lower and upper limbs, decreased pinprick sensation in stocking-glove pattern, and areflexia. Electrophysiological study revealed sensori-motor polyneuropathy, but did not suggest sufficient evidence of demyelination or axonal degeneration. Gene analysis identified c.22A>C Missense Mutation in the GJB1 gene. We report a CMT1X patient having typical X-linked dominant inheritance and missense mutation in the GJB1 gene.