title: More severe epilepsy and cognitive impairment in the offspring of a mother with mosaicism for the ring 20 chromosome.
abstract: OBJECTIVE
  Ring chromosome 20 [r(20)] syndrome is a rare chromosomal disorder. Cases tend to be sporadic. We elucidate the characteristics of an inherited r(20) mosaicism by describing the clinical features of three family members: a mother and her two children.
  
  
  RESULTS
  The mosaicism rate of the mother was 10% and that of the children 40%. The mother experienced her first epileptic seizures at 24 years of age. Epilepsy was diagnosed two years later. After an unstable period lasting 3 years, she has been seizure-free for 13 years on a combination of valproate and lamotrigine. She has normal intelligence with full working capacity. The daughter exhibited her first epileptic seizures at the age of 7 years and she continues to have seizures weekly. The first epileptic seizures in the son were observed at 5 years of age. The son's epilepsy has been drug resistant from the onset, and a vagal nerve stimulator (VNS) has been ineffective. Psychomotor development was normal in both children up to the onset of epilepsy. Learning difficulties increased throughout school age and both children needed special educational programs. Neuropsychological evaluations have shown deterioration of cognitive levels. Both children had behavioural problems during school age but no longer in adolescence. All three subjects are nondysmophic, normocephalic and of normal growth.
  
  
  CONCLUSIONS
  In this family the phenotype of r(20) mosaicism seems to be more severe in the successive generation along with a greater level of mosaicism. The aggravated clinical picture in inherited r(20) mosaicism concerned the onset of epilepsy, drug responsiveness, the cognitive level and behavioural features.
authors.affiliation: Kuopio Epilepsy Center, FIN-70211 Kuopio, Finland. eila.herrgard@kuh.fi
authors.forename: Eila
authors.initials: E
authors.lastname: Herrgård
authors.forename: Tarja
authors.initials: T
authors.lastname: Mononen
authors.forename: Esa
authors.initials: E
authors.lastname: Mervaala
authors.forename: Liisa
authors.initials: L
authors.lastname: Kuusela
authors.forename: Marja
authors.initials: M
authors.lastname: Aikiä
authors.forename: Ulla
authors.initials: U
authors.lastname: Stenbäck
authors.forename: Leena
authors.initials: L
authors.lastname: Pääkkönen
authors.forename: Raija-Liisa
authors.initials: RL
authors.lastname: Airaksinen
authors.forename: Reetta
authors.initials: R
authors.lastname: Kälviäinen
mesh_terms: D000293:Adolescent; D000328:Adult; D002890:Chromosomes, Human, Pair 20; D003072:Cognition Disorders / Q000235:genetics*; D004569:Electroencephalography; D004827:Epilepsy / Q000235:genetics* / Q000473:pathology; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000235:genetics; D008297:Male; D009030:Mosaicism; D012303:Ring Chromosomes