title: Familial clustering of seizure types within the idiopathic generalized epilepsies.
abstract: OBJECTIVE
  To examine the genetic relationships among epilepsies with different seizure types--myoclonic, absence, and generalized tonic-clonic--within the idiopathic generalized epilepsies (IGEs).
  
  
  BACKGROUND
  Careful phenotype definition in the epilepsies may allow division into groups that share susceptibility genes. Examination of seizure type, a phenotypic characteristic less complex than IGE syndrome, may help to define more homogeneous subgroups.
  
  
  METHODS
  Using the approach that found evidence of distinct genetic effects on myoclonic vs absence seizures in families from the Epilepsy Family Study of Columbia University, the authors examined an independent sample of families from Australia and Israel. They also examined the familial clustering of generalized tonic-clonic seizures (GTCs) within the IGEs in two combined data sets. Families were defined as concordant if all affected members had the same type of seizure or IGE syndrome, as appropriate for the analysis performed.
  
  
  RESULTS
  The proportion of families concordant for myoclonic vs absence seizures was greater than expected by chance in the Australian families. In addition, GTCs clustered in families with IGEs to a degree greater than expected by chance.
  
  
  CONCLUSIONS
  These results provide additional evidence for distinct genetic effects on myoclonic vs absence seizures in an independent set of families and suggest that there is a genetic influence on the occurrence of generalized tonic-clonic seizures within the idiopathic generalized epilepsies.
authors.affiliation: G.H. Sergievsky Center, Columbia University, New York, NY 10032, USA. mw211@columbia.edu
authors.forename: M R
authors.initials: MR
authors.lastname: Winawer
authors.forename: C
authors.initials: C
authors.lastname: Marini
authors.forename: B E
authors.initials: BE
authors.lastname: Grinton
authors.forename: D
authors.initials: D
authors.lastname: Rabinowitz
authors.forename: S F
authors.initials: SF
authors.lastname: Berkovic
authors.forename: I E
authors.initials: IE
authors.lastname: Scheffer
authors.forename: R
authors.initials: R
authors.lastname: Ottman
mesh_terms: D001315:Australia; D016000:Cluster Analysis; D004831:Epilepsies, Myoclonic / Q000453:epidemiology / Q000235:genetics; D004827:Epilepsy / Q000145:classification* / Q000453:epidemiology / Q000235:genetics*; D004832:Epilepsy, Absence / Q000453:epidemiology / Q000235:genetics; D004829:Epilepsy, Generalized / Q000453:epidemiology / Q000235:genetics; D004830:Epilepsy, Tonic-Clonic / Q000453:epidemiology / Q000235:genetics; D005192:Family Health; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006801:Humans; D007557:Israel; D008297:Male; D010641:Phenotype