title: Prenatal detection of isochromosome 21 by QF-PCR. A comparison between FISH and traditional karyotyping.
abstract: OBJECTIVE
  To compare rapid aneuploidy diagnostic tests with traditional karyotyping in the prenatal detection of Down syndrome due to isochromosome 21.
  
  
  METHODS
  Quantitative fluorescence PCR (QF-PCR) and fluorescent in situ hybridization (FISH) for chromosomes 13, 18, 21, X and Y were performed on uncultured amniotic fluid, followed by routine karyotyping. chromosomal and microsatellite analysis of peripheral blood from parents was also carried out.
  
  
  RESULTS
  The QF-PCR screening showed a trisomic diallelic pattern for 5 of 6 markers spanning the long arm of chromosome 21. FISH showed 3 signals in the interphase cells for the region 21q22.13-q22 during LSI 21 probe mapping. Cultured amniotic fluid revealed an isochromosome 21 resulting in a 46,XX,i(21)(q10),+21 karyotype. Parental microsatellite analysis proved that the isochromosome was paternal in origin.
  
  
  CONCLUSIONS
  The most informative analytical tool in this case appears to be QF-PCR, although a combination of QF-PCR and karyotyping provided the most evidence.
authors.affiliation: Department of Obstetrics and Gynaecology, National University Hospital, National University of Singapore, Singapore. leenagole@gmail.com
authors.forename: Leena
authors.initials: L
authors.lastname: Gole
authors.forename: Ng Bee
authors.initials: NB
authors.lastname: Lian
authors.forename: Ng Poh
authors.initials: NP
authors.lastname: Lian
authors.forename: Mary
authors.initials: M
authors.lastname: Rauff
authors.forename: Arijit
authors.initials: A
authors.lastname: Biswas
authors.forename: Mahesh
authors.initials: M
authors.lastname: Choolani
mesh_terms: D000328:Adult; D000649:Amniocentesis; D002891:Chromosomes, Human, Pair 21; D004314:Down Syndrome / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D018404:Isochromosomes; D007621:Karyotyping / Q000379:methods*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy
chemical_list: D005819:Genetic Markers