Real-world utility of whole exome sequencing with targeted gene analysis for focal epilepsy

Epilepsy Res. 2017 Mar;131:1-8. doi: 10.1016/j.eplepsyres.2017.02.001. Epub 2017 Feb 7.

Abstract

Objective: Driven by advances in genomic technology and reduction in costs, next-generation sequencing (NGS) is venturing into routine clinical care. The 'real-world' clinical utility of NGS remains to be determined in focal epilepsies, which account for 60% of all epilepsies and for which the importance of genetic factors is just beginning to emerge. We investigated the diagnostic yield and management implications of whole exome sequencing (WES)-based screening of selected genes in the routine care of common focal epilepsies suspected to have a genetic basis.

Methods: We performed WES, followed by targeted analysis of 64 epilepsy genes, on 40 consecutive children and adults enrolled prospectively from routine clinical practice who had MRI-negative focal epilepsy and a family history of febrile seizures or any type of epilepsy in at least one first- or second-degree relative. Exclusion criteria were previous genetic testing, severe intellectual disability and benign focal epilepsies of childhood.

Results: 5/40 (12.5%) patients had a pathogenic or likely pathogenic variant, detected in SCN1A, DEPDC5, PCDH19, GABRG2 or NPRL2. Identifying a pathogenic SCN1A variant in a patient with drug-resistant epilepsy prompted to halt presurgical investigations due to concern of unfavorable post-surgical outcome. It also led in the same patient to discontinue long-standing carbamazepine therapy (a potentially aggravating drug in epilepsies due to SCN1A mutations), resulting in complete seizure control. Patients with pathogenic or likely pathogenic variants had a younger median age of seizure onset (range) compared to those without [18 months (8 months-18 years) vs 18 years (18 months-70 years), p=0.02].

Significance: Our data demonstrate that WES with targeted gene analysis is an effective diagnostic tool for patients with common focal epilepsies in whom a genetic etiology is suspected. It can also influence clinical decision-making, including antiepileptic drug selection and consideration of epilepsy surgery, hence supporting its incorporation in the routine clinical care of this patient group.

Keywords: Epilepsy; Focal; Genetic testing; Genetics; Seizures.

Publication types

  • Multicenter Study
  • Pragmatic Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Child
  • Child, Preschool
  • Epilepsies, Partial / diagnosis*
  • Epilepsies, Partial / genetics*
  • Female
  • Genetic Testing / methods*
  • Genetic Variation / genetics*
  • Humans
  • Male
  • Middle Aged
  • Pedigree
  • Prospective Studies
  • Sequence Analysis, DNA / methods
  • Whole Exome Sequencing / methods*
  • Young Adult