第七届北京罕见病学术大会暨2019京津冀罕见病学术大会征文（124）

1Department of Neurology， Peking University First Hospital

2Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program， School of Life Sciences， Tsinghua University

Linchao Meng1， Kang Wang2， He Lv1， Zhaoxia Wang1， Wei Zhang1， Meng Yu1， Yiming Zheng1， Yinglin Leng1， Yun Yuan1

X-linked Charcot-Marie-Tooth disease-5 (CMTX5) is a rare hereditary disorders， caused by phosphoribosyl pyrophosphate synthetase 1 (PRSI) gene variation. We investigated a boy with a novel PRPS1 mutation (c.334G>C ， p.V112L) by extensive phenotyping， muscle MRI， and genetic， neuropathology and enzymatic tests. The proband was a 13-year-old boy with congenital non-syndromic sensorineural deafness. At the age of 3， he presented with distal weakness of all limbs with muscle atrophy of intrinsic hands and calves. Nerve conduction study revealed loss of sensory nerve action potential， slow of motor nerve conduction velocities with decrease of compound motor action potential amplitude. Visual evoked potential and auditory evoked potential were not evocable bilaterally. Sural biopsy proved loss of myelinated nerve fibers， with regenerating clusters and onion bulbs. Enzymatically， PRS-I activity was undetectable in the proband mild reduce in his mother and normal in control. To best of our knowledge this is first report of CMTX5 in Chinese population. The geneitc finding expand the genotypic spectrum of PRPS1 mutations.