POLG1 mutations cause a syndromic epilepsy with occipital lobe predilection.

Why are genetic evaluations important in epilepsy?  Do migraine phenomena overlap with epilepsy? JR

POLG1 mutations cause a syndromic epilepsy with occipital lobe predilection.

Bernt A Engelsen, Charalampos Tzoulis, Bj Karlsen, Atle Lillebø, Liv M Laegreid, Jan Aasly, Massimo Zeviani, Laurence A Bindoff

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1. Bernt A. Engelsen¹,²,
2. Charalampos Tzoulis²,
3. Bjørn Karlsen²,
4. Atle Lillebø²,
5. Liv M. Lægreid⁴,
6. Jan Aasly⁵,
7. Massimo Zeviani³ and
8. Laurence A. Bindoff¹,²

1. ¹Institute of Clinical Medicine, University of Bergen, ²Department of Neurology, Haukeland University Hospital, Bergen, Norway, ³Unit of Molecular Neurogenetics Pierfranco and Luisa Mariana Center for the Study of Children's Mitochondrial Disorders, National Neurological Institute “C.Besta”, via Temolo 4, 20133 Milan, Italy, ⁴Department of Paediatrics, Haukeland University Hospital, Bergen and ⁵St Olav's Hospital, Trondheim, Norway

1. Correspondence to: Bernt A. Engelsen and Laurence Bindoff, Department of Neurology, Haukeland University Hospital, Helse-Bergen, HF. N-5021 Bergen, Norway E-mail: bernt.engelsen{at}helse-bergen.no, laurence.bindoff{at}helse-bergen.no

• Received September 27, 2007.
• Revision received January 4, 2008.
• Accepted January 8, 2008.

Summary

The epileptic semiology of 19 patients (from 15 families) with mitochondrial disease due to mutations in the POLG1 gene is presented. The patients were either homozygous for the 1399G > A (p.A467T) or 2243G > C (p.W748S) mutations or compound heterozygotes for these two mutations. While the clinical features have been reviewed, detailed analysis of their epilepsy is presented for the first time. Irrespective of genotype, patients developed an epileptic syndrome with initial features of occipital lobe epilepsy. Occipital seizure phenomena included flickering coloured light, sometimes persisting for weeks, months or even years, ictal visual loss, horizontal/vertical nystagmus or oculoclonus, dysmorphopsia, micro-/macropsia and palinopsia. Most patients developed simple partial seizure phenomena with motor symptoms suggesting frontal lobe seizure initiation or spread. Simple and complex partial seizures, clonic- and/or myoclonic seizures with epilepsia partialis continua and frequent convulsive status epilepticus were observed in this syndrome that appears to be a symptomatic and secondary generalized or multifocal epilepsy with focal occipital predilection. The mean age of seizure presentation was 18.4 years (6–58 years). All patients developed status epilepticus and 11 patient deaths were, all related to prolonged convulsive status epilepticus, including two with liver failure apparently precipitated by treatment with sodium valproate.

• Abbreviations:

  Abbreviations:

  SE

  status epilepticus

  C-/NC

  convulsive/non-convulsive

  SPS

  simple partial seizure

  CPS

  complex partial seizure

  PLEDS

  periodic lateralized epileptic discharges

  sGTC

  secondary generalized tonic–clonic seizures

  EPC

  epilepsia partialis continua