title: Mild phenotype of Charcot-Marie-Tooth disease type 4B1.
abstract: Charcot-Marie-Tooth type 4B1 (CMT4B1) is a rare autosomal recessive demyelinating neuropathy caused by mutation of the myotubularin-related 2 (MTMR2) gene. It is characterized by a severe early-onset motor and sensory neuropathy, and myelin outfoldings on nerve biopsy. We describe a mild phenotype of CMT4B1 in a Japanese patient. She noticed difficulty in walking as an initial symptom at age 13. Her symptoms progressed slowly, and she could still walk at age 34. There was no cranial neuropathy. A nerve conduction study demonstrated demyelinating neuropathy. Sural nerve biopsy revealed a moderate-to-severe loss of myelinated fibers, and many focally folded myelin sheaths. Electron micrographs showed myelin outfoldings and infoldings. DNA tests for CMT showed that she is a homozygote for the MTMR2 p.R628PfsX18 mutation. The mild phenotype in our patient is probably due to the C-terminal position of the frame-shift mutation in MTMR2.
authors: Department of Neurology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan. Electronic address: tatsum@med.kawasaki-m.ac.jp.
authors: Tatsufumi
authors: T
authors: Murakami
authors: Yumiko
authors: Y
authors: Kutoku
authors: Hirotake
authors: H
authors: Nishimura
authors: Makiko
authors: M
authors: Hayashi
authors: Akiko
authors: A
authors: Abe
authors: Kiyoshi
authors: K
authors: Hayasaka
authors: Yoshihide
authors: Y
authors: Sunada
mesh_terms: D000328:Adult; D002607:Charcot-Marie-Tooth Disease / Q000235:genetics* / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D009154:Mutation; D009186:Myelin Sheath / Q000473:pathology; D010641:Phenotype; D054558:Protein Tyrosine Phosphatases, Non-Receptor / Q000235:genetics*; D013497:Sural Nerve / Q000473:pathology* / Q000648:ultrastructure; D013979:Tibial Nerve / Q000503:physiopathology*
chemical_list: C408986:MTMR2 protein, human; D054558:Protein Tyrosine Phosphatases, Non-Receptor
keywords: Charcot–Marie–Tooth disease type 4B1; Mild phenotype; Myelin outfoldings; Myotubularin-related 2 gene; PDZ-binding domain; Sporadic CMT