title: Rapid positive confirmation of mosaicism for a small supernumerary marker chromosome as r(8) by interphase fluorescence in situ hybridization, quantitative fluorescent polymerase chain reaction, and array comparative genomic hybridization on uncultured amniocytes in a pregnancy with fetal pyelectasis.
abstract: OBJECTIVE
  This study aimed at presenting prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome (sSMC) derived from chromosome 8 by fluorescence in situ hybridization (FISH), quantitative fluorescent polymerase chain reaction (QF-PCR), and array comparative genomic hybridization (aCGH) on uncultured amniocytes.
  
  
  RESULTS
  A 32-year-old woman underwent amniocentesis at 19 weeks of gestation because of fetal pyelectasis. Amniocentesis revealed a de novo ring-shaped sSMC in two of 21 colonies of cultured amniocytes. Repeated amniocentesis at 22 weeks of gestation revealed a karyotype of 47,XY,+mar[8]/46,XY[32] in cultured amniocytes. Spectral karyotyping and FISH confirmed that the sSMC was derived from chromosome 8. She underwent a third amniocentesis at 26 weeks of gestation. Oligonucleotide-based aCGH analysis on uncultured amniocytes demonstrated a 43 Mb genomic gain in chromosome 8 encompassing 8p22→q12.1. Polymorphic DNA marker analysis of the uncultured amniocytes revealed a maternal origin of the sSMC and excluded uniparental disomy 8. Interphase FISH analysis showed three D8Z2 signals in 8/40 (20%) of uncultured amniocytes. The cultured amniocytes had a karyotype of 47,XY,+r(8)(p22q12.1)[3]/46,XY[37]. The pregnancy was carried to term, and an apparently normal baby, weighing 3300 g, was delivered with mild hydronephrosis but no other phenotypic abnormalities. The cord blood was found to have a karyotype of 47,XY,+r(8)(p22q12.1)[2]/46,XY[38].
  
  
  CONCLUSIONS
  Prenatal diagnosis of fetal pyelectasis should alert obstetricians of chromosome aberration. Interphase FISH, QF-PCR, and aCGH analyses on uncultured amniocytes are helpful in rapid positive confirmation of an sSMC detected at amniocentesis.
authors.affiliation: Department of Medicine, Mackay Medical College, New Taipei City, Taiwan. cpc_mmh@yahoo.com
authors.forename: Chih-Ping
authors.initials: CP
authors.lastname: Chen
authors.forename: Shuenn-Dyh
authors.initials: SD
authors.lastname: Chang
authors.forename: Yi-Ning
authors.initials: YN
authors.lastname: Su
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Schu-Rern
authors.initials: SR
authors.lastname: Chern
authors.forename: Jun-Wei
authors.initials: JW
authors.lastname: Su
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Chen
authors.forename: Wen-Lin
authors.initials: WL
authors.lastname: Chen
authors.forename: Chen-Wen
authors.initials: CW
authors.lastname: Pan
authors.forename: Meng-Shan
authors.initials: MS
authors.lastname: Lee
authors.forename: Wayseen
authors.initials: W
authors.lastname: Wang
mesh_terms: D000328:Adult; D000649:Amniocentesis; D002869:Chromosome Aberrations; D002898:Chromosomes, Human, Pair 8; D055028:Comparative Genomic Hybridization; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D009030:Mosaicism; D016133:Polymerase Chain Reaction / Q000379:methods; D011247:Pregnancy; D058536:Pyelectasis / Q000175:diagnosis / Q000235:genetics*