title: Mosaic trisomy 12 at amniocentesis: prenatal diagnosis and molecular genetic analysis.
abstract: OBJECTIVE
  This study is aimed at prenatal diagnosis of mosaic trisomy 12 and reviewing the literature.
  
  
  METHODS
  A 34-year-old woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Cytogenetic analysis of cultured amniocytes revealed a karyotype of 47,XX,+12[9]/46,XX[14]. She was referred to the hospital for genetic counseling. Repeated amniocentesis was performed at 22 weeks of gestation. Array comparative genomic hybridization (aCGH), interphase fluorescence in situ hybridization (FISH) and quantitative fluorescent polymerase chain reaction (QF-PCR) were applied on uncultured amniocytes, and conventional cytogenetic analysis was applied on cultured amniocytes.
  
  
  RESULTS
  The aCGH analysis on uncultured amniocytes revealed a small genomic gain in chromosome 12. Interphase FISH analysis on uncultured amniocytes using a 12q11-q12-specific probe of RP11-496H24 (green spectrum) showed three green signals in 17.8% (8/45 cells) of uncultured amniocytes. QF-PCR analysis on uncultured amniocytes using chromosome 12-specific microsatellite markers excluded uniparental disomy 12. Cytogenetic analysis of cultured amniocytes revealed a karyotype of 47,XX,+12[5]/46,XX[25]. The parents decided to continue the pregnancy. A healthy 3270 g female baby was delivered at 39 weeks of gestation, with no phenotypic abnormalities. Cytogenetic analysis of the cord blood revealed a karyotype of 46,XX in 40/40 cultured lymphocytes. The neonate was normal in growth and psychomotor development at 6 months of age. Interphase FISH analysis on uncultured urinary cells revealed 5% (1/20 cells) mosaicism for trisomy 12.
  
  
  CONCLUSIONS
  Prenatal diagnosis of mosaic trisomy 12 at amniocentesis should alert a clinically significant aneuploidy. Interphase FISH and aCGH on uncultured amniocytes are useful for rapid confirmation of low-level trisomy 12 mosaicism at repeated amniocentesis.
authors.affiliation: Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan. cpc_mmh@yahoo.com
authors.forename: Chih-Ping
authors.initials: CP
authors.lastname: Chen
authors.forename: Yi-Ning
authors.initials: YN
authors.lastname: Su
authors.forename: Jun-Wei
authors.initials: JW
authors.lastname: Su
authors.forename: Schu-Rern
authors.initials: SR
authors.lastname: Chern
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Chen
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Chen
authors.forename: Wayseen
authors.initials: W
authors.lastname: Wang
mesh_terms: D000328:Adult; D000649:Amniocentesis; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D055028:Comparative Genomic Hybridization; D005260:Female; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007231:Infant, Newborn; D009030:Mosaicism; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D014314:Trisomy / Q000175:diagnosis* / Q000235:genetics