title: Post-zygotic origin of isochromosome 12p.
abstract: OBJECTIVE
  Advance knowledge about the mechanism of isochromosome formation.
  
  
  METHODS
  Echographic examination of the foetus. G- and/or T-banded chromosome and FISH analysis using chromosome 12p subtelomeric probes on short- and long-term CVS cultures, amniocytes and foetal fibroblasts. Polymorphic CA repeat analysis on DNA from the foetus and both parents.
  
  
  RESULTS
  Short-term CVS cultures showed a 46,XX karyotype, whilst long-term CVS cultures showed a 47,XX,+12 karyotype. FISH on amniocytes indicated 2, 3 and 4 signals. Foetal fibroblasts showed both 47,XX,+12 and 47,XX,+i(12)(p10) karyotypes. DNA analysis revealed the isochromosome to be paternal in origin, whilst the other two foetal chromosomes 12 were maternal, part iso- and part heterodisomy.
  
  
  CONCLUSIONS
  The cytogenetic and DNA constitution of the foetus indicated the isochromosome 12p to be of paternal origin, and implied post-zygotic formation of the isochromosome 12p in the Pallister-Killian syndrome.
authors.affiliation: Centre for Human Genetics, UZ Gasthuisberg, Katholieke Universiteit Leuven, Herestraat 49, B-3000 Leuven, Belgium. Thomy.deRavel@uz.kuleuven.ac.be
authors.forename: Thomy J L
authors.initials: TJ
authors.lastname: de Ravel
authors.forename: Kathelijn
authors.initials: K
authors.lastname: Keymolen
authors.forename: Elvire
authors.initials: E
authors.lastname: van Assche
authors.forename: Ingrid
authors.initials: I
authors.lastname: Wittevronghel
authors.forename: Philippe
authors.initials: P
authors.lastname: Moerman
authors.forename: Ivo
authors.initials: I
authors.lastname: Salden
authors.forename: Gert
authors.initials: G
authors.lastname: Matthijs
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Fryns
authors.forename: Joris R
authors.initials: JR
authors.lastname: Vermeesch
mesh_terms: D000328:Adult; D000483:Alleles; D000653:Amniotic Fluid / Q000166:cytology; D002478:Cells, Cultured; D002824:Chorionic Villi / Q000648:ultrastructure; D002871:Chromosome Banding; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics*; D004247:DNA / Q000032:analysis; D005260:Female; D005347:Fibroblasts; D005865:Gestational Age; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D018404:Isochromosomes / Q000235:genetics*; D007621:Karyotyping; D011247:Pregnancy; D011296:Prenatal Diagnosis; D015053:Zygote
chemical_list: D004247:DNA