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Genetic epilepsy with febrile seizures plus: definite and borderline phenotypes
  1. R H Thomas1,2,3,
  2. J A Johnston1,2,3,
  3. C L Hammond1,3,4,
  4. S Bagguley2,
  5. C White3,5,
  6. P E Smith2,3,
  7. M I Rees1,3
  1. 1Institute of Life Sciences, College of Medicine, Swansea University, UK
  2. 2Neurology Department, University Hospital of Wales, Cardiff University, UK
  3. 3Wales Epilepsy Research Network (WERN), College of Medicine, Swansea University, UK
  4. 4Guy's Hospital, London, UK
  5. 5Department of Paediatric Neurology, Morriston Hospital, Swansea, UK
  1. Correspondence to Dr R H Thomas, Institute of Life Sciences, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK; rhys-thomas{at}


Generalised epilepsy with febrile seizures plus (GEFS+) is the most studied familial epilepsy syndrome. However, characteristics of UK families have not previously been reported. Among the first 80 families recruited to our families study, four broad subphenotypes were identified: families with classical GEFS+; families with borderline GEFS+; families with unclassified epilepsy; and families with an alternative syndromal diagnosis. Borderline GEFS+ families shared many characteristics of classical GEFS+ families—such as prominent febrile seizures plus and early onset febrile seizures—but included more adults with focal epilepsies (rather than the idiopathic generalised epilepsies predominating in GEFS+) and double the prevalence of migraine. Thus the authors believe that a novel and robust familial epilepsy phenotype has been identified. Subcategorising families with epilepsy is helpful in targeting both clinical and research resources. Most families with GEFS+ have no identified causal mutation, and so predicting genetic homogeneity by identifying endophenotypes becomes more important.

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  • Funding The Wales Epilepsy Research Network is funded through the Wales Office of Research and Development (WORD) and the National Institute for Social Care and Health Research (NISCHR).

  • Competing interests None.

  • Ethics approval The study was approved by the South West Wales research ethics committee (MREC approval 05/MRE09/78).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement We would only be happy to share anonymised individual or familial phenotype information within the context of a formal collaboration because of the nature of our ethics agreement.