title: Detection of no isochromosome 20q by interphase fluorescent in situ hybridization on uncultured amniocytes in a pregnancy with mosaic isochromosome 20q in cultured amniocytes at amniocentesis.
abstract: OBJECTIVE
  To present prenatal diagnosis and molecular cytogenetic characterization of mosaic isochromosome 20q at amniocentesis.
  
  
  METHODS
  A 36-year-old woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age, and conventional cytogenetic analysis revealed a karyotype of 46,XY,i(20)(q10)[12]/46,XY[7]. Repeated amniocentesis was performed at 20 weeks of gestation. During repeated amniocentesis, array comparative genomic hybridization (aCGH), interphase fluorescence in situ hybridization (FISH), and quantitative fluorescent polymerase chain reaction (QF-PCR) were performed on uncultured amniocytes, and conventional cytogenetic analysis and interphase FISH were performed on cultured amniocytes.
  
  
  RESULTS
  Conventional cytogenetic analysis of cultured amniocytes revealed a karyotype of 46,XY,i(20)(q10)[4]/46,XY[16]. Interphase FISH analysis on 217 uncultured amniocytes did not detect isochromosome 20q, aCGH on the DNA extracted from uncultured amniocytes showed no genomic imbalance, and QF-PCR analysis on the DNA extracted from uncultured amniocytes excluded uniparental disomy 20 (UPD 20). Interphase FISH analysis on 115 cultured untouched amniocytes revealed 13% (15/115 cells) mosaicism for isochromosome 20q.
  
  
  CONCLUSIONS
  Mosaic isochromosome 20q detected at amniocentesis can be a cell culture artifact. Detailed ultrasound examination, performing interphase FISH and/or aCGH on uncultured amniocytes for confirmation of true mosaicism, and performing QF-PCR to exclude UPD 20 may be useful under such a circumstance.
authors: Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan; Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan; Department of Biotechnology, Asia University, Taichung, Taiwan; School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan; Institute of Clinical and Community Health Nursing, National Yang-Ming University, Taipei, Taiwan; Department of Obstetrics and Gynecology, School of Medicine, National Yang-Ming University, Taipei, Taiwan. Electronic address: cpc_mmh@yahoo.com.
authors: Chih-Ping
authors: CP
authors: Chen
authors: Department of Obstetrics and Gynecology, China Medical University Hospital, Taichung, Taiwan.
authors: Jun-Wei
authors: JW
authors: Su
authors: Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan.
authors: Schu-Rern
authors: SR
authors: Chern
authors: Department of Obstetrics and Gynecology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors: Yu-Ling
authors: YL
authors: Kuo
authors: Gene Biodesign Co. Ltd, Taipei, Taiwan.
authors: Peih-Shan
authors: PS
authors: Wu
authors: Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
authors: Meng-Shan
authors: MS
authors: Lee
authors: Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan.
authors: Chien-Wen
authors: CW
authors: Yang
authors: Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan; Department of Bioengineering, Tatung University, Taipei, Taiwan.
authors: Wayseen
authors: W
authors: Wang
mesh_terms: D000328:Adult; D000649:Amniocentesis / Q000379:methods*; D000650:Amnion / Q000166:cytology*; D002478:Cells, Cultured; D002890:Chromosomes, Human, Pair 20 / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D020732:Cytogenetic Analysis / Q000379:methods; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D018404:Isochromosomes / Q000235:genetics*; D007621:Karyotyping; D008423:Maternal Age; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011296:Prenatal Diagnosis; D024182:Uniparental Disomy / Q000175:diagnosis* / Q000235:genetics
keywords: amniocentesis; amniocytes; isochromosome 20q; mosaicism; prenatal diagnosis