title: Prenatal diagnosis and molecular cytogenetic characterization of low-level true mosaicism for trisomy 21 using uncultured amniocytes.
abstract: OBJECTIVE
  We present a prenatal diagnosis and molecular cytogenetic characterization of low-level true mosaicism for trisomy 21 using uncultured amniocytes.
  
  
  METHODS
  A 35-year-old woman presented with a borderline-positive result of noninvasive prenatal testing for trisomy 21. She underwent amniocentesis at 18 weeks of gestation, which revealed a karyotype of 47,XY,+21(5)/46,XY(53). Repeat amniocentesis at 22 weeks of gestation revealed a karyotype of 47,XY,+21(6)/46,XY(26). Array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes revealed mosaic levels of 10% to 15% for trisomy 21. Interphase fluorescence in situ hybridization (FISH) analysis on uncultured amniocytes revealed a mosaic level of 21.7% (28/129 cells) for trisomy 21. Following genetic counseling and detailed ultrasound examination, the parents decided to continue the pregnancy. The pregnancy was carried to term, and a normal 3664-g male baby was delivered. The cord blood lymphocytes had a karyotype of 47,XY,+21(2)/46,XY(38). Postnatal interphase FISH analysis of urine detected no trisomy 21 in all 39/39 urinary cells. The neonate was phenotypically normal at age 7 months.
  
  
  CONCLUSIONS
  Low-level true mosaicism for trisomy 21 can be associated with a favorable fetal outcome. aCGH and interphase FISH analyses on uncultured amniocytes are useful for rapid confirmation of low-level true mosaicism for trisomy 21 at repeated amniocentesis.
authors.affiliation: 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.forename: Chih-Ping
authors.initials: CP
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan; Mackay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan.
authors.forename: Yeou-Lih
authors.initials: YL
authors.lastname: Wang
authors.affiliation: Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Schu-Rern
authors.initials: SR
authors.lastname: Chern
authors.affiliation: Gene Biodesign Co. Ltd, Taipei, Taiwan.
authors.forename: Peih-Shan
authors.initials: PS
authors.lastname: Wu
authors.affiliation: Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Yen-Ni
authors.initials: YN
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Shin-Wen
authors.initials: SW
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Meng-Shan
authors.initials: MS
authors.lastname: Lee
authors.affiliation: Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Chien-Wen
authors.initials: CW
authors.lastname: Yang
authors.affiliation: Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan; Department of Bioengineering, Tatung University, Taipei, Taiwan.
authors.forename: Wayseen
authors.initials: W
authors.lastname: Wang
mesh_terms: D059786:Abnormal Karyotype; D000328:Adult; D000649:Amniocentesis; D000650:Amnion / Q000166:cytology; D055028:Comparative Genomic Hybridization; D004314:Down Syndrome / Q000175:diagnosis* / Q000235:genetics*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009030:Mosaicism; D011247:Pregnancy; D011296:Prenatal Diagnosis
keywords: aCGH; interphase FISH; mosaicism; trisomy 21; uncultured amniocytes