title: Trisomy 7 mosaicism at amniocentesis: interphase FISH, QF-PCR, and aCGH analyses on uncultured amniocytes for rapid distinguishing of true mosaicism from pseudomosaicism.
abstract: OBJECTIVE
  To present prenatal diagnosis of true trisomy 7 mosaicism.
  
  
  RESULTS
  A 36-year-old woman underwent amniocentesis at 18 weeks of gestation. Amniocentesis revealed a karyotype of 47,XY,+7[20]/46,XY[9]. The parental karyotypes were normal. Repeated amniocentesis was performed at 20 weeks of gestation. Array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes manifested a genomic gain in chromosome 7. Quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on uncultured amniocytes showed a biparental diallelic pattern with a dosage increase in the maternal allele. Interphase fluorescence in situ hybridization (FISH) on uncultured amniocytes revealed three 7q-specific signals in 13 of 50 (26%) of the cells. The cultured amniocytes had a karyotype of 47,XY,+7[12]/46,XY[14]. The ultrasound findings were unremarkable. The pregnancy was subsequently terminated, and a fetus was delivered with facial dysmorphisms. Postnatal tissue samplings revealed the mosaic trisomy 7 level of 37.5% (15/40), 30% (12/40), 42.5% (17/40), 82.5% (33/40), 52.5% (21/40), and 27.5% (11/40) in skin, liver, lungs, placenta, membrane, and cord, respectively. The cord blood had a karyotype of 46,XY. PEG1/MEST methylation-sensitive high-resolution melting PCR assay of cord blood showed no uniparental disomy for chromosome 7.
  
  
  CONCLUSIONS
  Interphase FISH, QF-PCR, and aCGH analyses on uncultured amniocytes are useful for rapid distinguishing of true mosaicism from pseudomosaicism for trisomy 7 at amniocentesis. Cord blood sampling for confirmation of fetal trisomy 7 mosaicism is not practical.
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: Hsu-Kuang
authors.initials: HK
authors.lastname: Huang
authors.forename: Yi-Ning
authors.initials: YN
authors.lastname: Su
authors.forename: Schu-Rern
authors.initials: SR
authors.lastname: Chern
authors.forename: Jun-Wei
authors.initials: JW
authors.lastname: Su
authors.forename: Chen-Chi
authors.initials: CC
authors.lastname: Lee
authors.forename: Dai-Dyi
authors.initials: DD
authors.lastname: Town
authors.forename: Wen-Lin
authors.initials: WL
authors.lastname: Chen
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Chen
authors.forename: Wayseen
authors.initials: W
authors.lastname: Wang
mesh_terms: D000328:Adult; D000649:Amniocentesis; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics; D055028:Comparative Genomic Hybridization; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007399:Interphase; D059785:Karyotype; D009030:Mosaicism; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011296:Prenatal Diagnosis; D014314:Trisomy / Q000175:diagnosis* / Q000235:genetics*; D024182:Uniparental Disomy / Q000175:diagnosis* / Q000235:genetics*