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A variable neurodegenerative phenotype with polymerase γ mutation
  1. S Stricker1,
  2. H Prüss1,
  3. R Horvath2,3,
  4. E Baruffini4,
  5. T Lodi4,
  6. E Siebert5,
  7. M Endres1,6,
  8. R Zschenderlein1,
  9. A Meisel1
  1. 1
    Department of Neurology, Charité Universitaetsmedizin Berlin, Berlin, Germany
  2. 2
    Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, Munich, Germany
  3. 3
    Mitochondrial Research Group, University of Newcastle, Newcastle, UK
  4. 4
    Department of Genetics, Biology of Microorganisms, Anthropology, Evolution, University of Parma, Parma, Italy
  5. 5
    Department of Neuroradiology, Charité Universitaetsmedizin Berlin, Berlin, Germany
  6. 6
    Centrum für Schlaganfallforschung Berlin (CSB), Berlin, Germany
  1. Correspondence to Dr S Stricker, Charité Universtitaetsmedizin Berlin, Department of Neurology, Charitéplatz 1, 10117 Berlin, Germany; sarah.stricker{at}charite.de

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Deficiency of mitochondrial DNA polymerase γ (POLG), which is responsible for mtDNA replication and repair, causes mitochondrial diseases including autosomal dominant progressive external ophthalmoplegia (PEO),1 childhood hepato-encephalopathy (Alpers–Huttenlocher syndrome), adult-onset spinocerebellar ataxia, and sensory nerve degeneration with dysarthria and ophthalmoparesis (SANDO).2 3

Case reports

Two siblings of non-consanguineous healthy Vietnamese parents were normal until childhood (fig 1A,B).

Figure 1

(A) Clinical course of the sister (II.3) and the brother (II.2) with MRI of the sister revealing cortical lesions and cerebellar T2-hyperintensities (arrow) and the brother’s MRI showing leucoencephalopathy and cerebellar T2-hyperintensities. (B) Family pedigree with polymerase γ 1 (POLG1) mutations. Squares represent males, circles females, filled symbols affected and slashed symbols deceased individuals. (C) Mutant residues in POLG1 and amino-acid alignment showing evolutionary conservation of altered residues.

Patient II.2, the 27-year-old male, developed from the age of 15 progressive cerebellar ataxia, neuropathy, restless legs syndrome, on two occasions a transient left hemihypesthesia and four focal myoclonic epileptic seizures and received lamotrigine. He became wheelchair-bound at 22 because of severe ataxia. By 25, he developed dysphagia and weight loss. Muscle strength was preserved. No external ophthalmoplegia or cognitive deficits occurred. After discontinuing lamotrigine, he exhibited grand maux, requiring combination treatment. He became anxious and complained of migrainous headaches and abdominal pain. Soon after, he died after prolonged status epilepticus.

Lactate-ischaemia ergometry at age 20 was unremarkable. In serum, lactate and CK (244 U/l) were mildly elevated. In CSF, …

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