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Mitochondrial disease mimicking Charcot–Marie Tooth disease
  1. M Needham1,
  2. J Duley2,
  3. S Hammond3,
  4. G.K. Herkes4,
  5. M Hirano5,
  6. C M Sue6
  1. 1Department of Neurology, Royal North Shore Hospital and University of Sydney, Sydney, New South Wales, Australia
  2. 2Chemical Pathology, Mater Health Services, Brisbane, Australia
  3. 3Department of Neurology, Orange Base Hospital, Sydney, New South Wales, Australia
  4. 4Department of Neurology, Royal North Shore Hospital and University of Sydney, New South Wales, Australia
  5. 5Department of Neurology, College of Physicans and Surgeons, Columbia University, New York City, New York, USA
  6. 6Department of Neurology, Royal North Shore Hospital and University of Sydney, New South Wales, Sydney, Australia
  1. Correspondence to:
 C M Sue
 Department of Neurogenetics, Clinic 4, Royal North Shore Hospital, Reserve Rd, St Leonards, Sydney, New South Wales 2065, Australia; csue{at}med.usyd.edu.au

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Patient 1 was a 24-year-old woman with a 12-year history of a progressive sensorimotor peripheral neuropathy associated with pes cavus and bilateral foot drop. She had no family history of neuromuscular disease. At the age of 20 years she underwent nerve conduction studies (NCS), which showed absent motor and sensory responses in the lower limbs, with reduced upper limb motor conduction velocities (table). Upper limb sensory nerve action potentials (SNAP) were also absent. Interestingly, she had a lumbar puncture that showed no cells but a raised protein concentration of 1.56 mmol/l. A sural nerve biopsy showed active chronic axonal neuropathy with some segmental demyelination, not consistent with chronic inflammatory demyelinating polyneuroapthy (CIDP). Her muscle biopsy showed neuropathic changes with a mild inflammatory infiltrate. Genetic testing for X-linked Charcot–Marie Tooth disease (CMT) 1A, 1B and X-linked was negative. Four years later, she developed an external ophthalmoplegia, increasing abdominal borborygmi, pain, nausea, vomiting and diarrhoea, associated with considerable weight loss. Urinary thymidine levels (92 μmol/mmol creatinine) and deoxyuridine (168 μmol/mmol creatinine) were markedly raised. DNA sequencing showed compound heterozygotic mutations (G106T and del-G at nucleotide 1444) in the thymidine phosphorylase gene, confirming the diagnosis of mitochondrial myopathy, neuropathy and gastrointestinal encephalopathy (MNGIE) syndrome.

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Table Representative nerve conduction studies of patients …

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