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.
Keywords
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Article info
Publication history
Published online: August 19, 2013
Accepted:
August 1,
2013
Received in revised form:
July 9,
2013
Received:
February 18,
2013
Identification
Copyright
© 2013 Elsevier B.V. Published by Elsevier Inc. All rights reserved.
