title: Ring chromosome 20 syndrome: electroclinical description of six patients and review of the literature.
abstract: BACKGROUND
  Ring chromosome 20 syndrome is a rare chromosomal disorder.
  
  
  METHODS
  In six patients, we focused on the presenting epileptic phenotype, the behavioral and mental problems and the relationship between the ratio of mosaicism and the age at onset of the epilepsy.
  
  
  RESULTS
  All patients presented with pharmacoresistant frontal lobe complex partial seizures. The earliest onset of epilepsy was seen in patients without mosaicism. There were three patients out of six with behavioral disturbances before the onset of seizures. All patients had mild to moderate cognitive impairment. Electroencephalogram recordings showed rhythmic theta waves with frontal predominance and non-convulsive status epilepticus (NCSE).
  
  
  CONCLUSIONS
  The ring chromosome 20 syndrome is characterized by childhood-onset refractory epilepsy continuing throughout adult life, mental disability, and behavioral disturbances which can originate before seizure onset. Ictal EEG reveals a unique pattern. Our findings indicate a possible link between the percentage of affected cells and the age of epilepsy onset.
authors.affiliation: Department of Paediatric Neurology, University Hospital Leuven, Belgium.
authors.forename: Iris
authors.initials: I
authors.lastname: Elens
authors.forename: Katrien
authors.initials: K
authors.lastname: Vanrykel
authors.forename: Liesbeth
authors.initials: L
authors.lastname: De Waele
authors.forename: Katrien
authors.initials: K
authors.lastname: Jansen
authors.forename: Merel
authors.initials: M
authors.lastname: Segeren
authors.forename: Wim
authors.initials: W
authors.lastname: Van Paesschen
authors.forename: Berten
authors.initials: B
authors.lastname: Ceulemans
authors.forename: Marc
authors.initials: M
authors.lastname: Boel
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Frijns
authors.forename: Gunnar
authors.initials: G
authors.lastname: Buyse
authors.forename: Lieven
authors.initials: L
authors.lastname: Lagae
mesh_terms: D000368:Aged; D000927:Anticonvulsants / Q000627:therapeutic use; D058256:Brain Waves / Q000235:genetics / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D002890:Chromosomes, Human, Pair 20 / Q000235:genetics*; D004569:Electroencephalography; D004827:Epilepsy / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012303:Ring Chromosomes; D055815:Young Adult
chemical_list: D000927:Anticonvulsants