title: Genetics of febrile seizure subtypes and syndromes: a twin study.
abstract: OBJECTIVE
  Febrile seizures (FS) are the most common seizure syndrome. A strong genetic component has been well established through family and twin studies; however, such studies have not examined the genetics of different FS types (simple, complex, febrile status epilepticus) and sub-syndromes (true FS, febrile seizures plus (FS+), 'FS with later epilepsy'). Here we used a community-based twin sample to analyze genetic factors within different FS subtypes and FS syndromes.
  
  
  METHODS
  Twin pairs were ascertained from the twin database of the Epilepsy Research Centre. A retrospective chart review was conducted and follow-up attempted for all subjects. Casewise concordance values were calculated for the different subgroups and intra-pair variation was analyzed.
  
  
  RESULTS
  One hundred and seventy-nine twin pairs with FS were identified. Overall casewise concordance for FS in monozygotic (MZ) twins (0.62) was greater than in dizygotic (DZ) twins (0.16, p<0.0001). A greater concordance amongst MZ pairs than DZ twin pairs was also observed for all FS subtypes and FS sub-syndromes, particularly in twins with FS+. Within concordant MZ pairs, we did not observe the co-occurrence of FS and FS+.
  
  
  CONCLUSIONS
  These results suggest a strong genetic contribution to different FS subtypes and sub-syndromes. They also support the existence of distinct genetic factors for different FS subtypes and sub-syndromes, especially FS+. This information is important for the strategic planning of next generation sequencing studies of febrile seizures.
authors.affiliation: Epilepsy Research Centre and Department of Medicine (Neurology), University of Melbourne, Austin Health, Heidelberg, Victoria, Australia.
authors.forename: Jazmin
authors.initials: J
authors.lastname: Eckhaus
authors.forename: Kate M
authors.initials: KM
authors.lastname: Lawrence
authors.forename: Ingo
authors.initials: I
authors.lastname: Helbig
authors.forename: Minh
authors.initials: M
authors.lastname: Bui
authors.forename: Lata
authors.initials: L
authors.lastname: Vadlamudi
authors.forename: John L
authors.initials: JL
authors.lastname: Hopper
authors.forename: Ingrid E
authors.initials: IE
authors.lastname: Scheffer
authors.forename: Samuel F
authors.initials: SF
authors.lastname: Berkovic
mesh_terms: D002648:Child; D002675:Child, Preschool; D004200:Diseases in Twins / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D012042:Registries; D012189:Retrospective Studies; D003294:Seizures, Febrile / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*