title: Partial trisomy 8 mosaicism not detected by cultured amniotic-fluid cells.
abstract: OBJECTIVE
  Prenatal detection of trisomy 8 mosaicism can be misleading and remains challenging in genetic counseling. Identifying cases of partial or complete trisomy 8 mosaicism will highlight the pitfalls of conventional karyotyping in prenatal amniocentesis for partial or complete trisomy 8 mosaicism.
  
  
  METHODS
  The patient was born uneventfully at term to a healthy 34-year-old mother. Analysis of the amniotic fluid (AF) cells showed a normal male karyotype. At birth, the newborn presented dysmorphic features, including asymmetric mandibles and ears, anteverted nostrils with a relatively long philtrum, retrognathia, and a clenched hand on the left side. Imaging studies revealed agenesis of the corpus callosum with bilateral colpocephaly, a common arterial trunk bifurcating into the left subclavian and carotid arteries, and bilateral pelviectasis. Cytogenetic analysis of the blood revealed mosaicism of partial trisomy 8: 47,XY,+del(8) (q21.3) [8]/46,XY [12]. Array comparative genomic hybridization (array-CGH) revealed 82.9 Mb duplications at chromosome 8p23.3-8q21.3 with dosage variations. Interphase fluorescence in situ hybridization analysis of urine sediments and buccal smears were compatible with mosaic compositions. A small colony of AF cells was found to have partial trisomy 8 in repeated analysis.
  
  
  CONCLUSIONS
  Conventional karyotyping through amniocentesis has limitations particularly in detecting rare trisomy mosaicism if trisomic cells show growth disadvantage. Array-CGH using uncultured cells may be of help in providing more information on genetic dosage variations in such cases.
authors.affiliation: Department of Pediatrics, National Cheng Kung University Hospital and College of Medicine, Tainan, Taiwan.
authors.forename: Meng-Che
authors.initials: MC
authors.lastname: Tsai
authors.affiliation: Cytogenetic Laboratory, Department of Pathology, National Cheng Kung University Hospital, Tainan, Taiwan.
authors.forename: Hsueh-Yin
authors.initials: HY
authors.lastname: Cheng
authors.affiliation: Department of Obstetrics and Gynecology, National Cheng Kung University Hospital and College of Medicine, Tainan, Taiwan.
authors.forename: Mei-Tsz
authors.initials: MT
authors.lastname: Su
authors.affiliation: Department of Genomic Medicine and Center for Medical Genetics, Changhua Christian Hospital, Changhua, Taiwan.
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynecology, National Cheng Kung University Hospital and College of Medicine, Tainan, Taiwan. Electronic address: paolink@mail.ncku.edu.tw.
authors.forename: Pao-Lin
authors.initials: PL
authors.lastname: Kuo
mesh_terms: D000328:Adult; D000649:Amniocentesis; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics; D055028:Comparative Genomic Hybridization; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D009030:Mosaicism; D011247:Pregnancy; D014314:Trisomy / Q000175:diagnosis* / Q000235:genetics; D024182:Uniparental Disomy / Q000175:diagnosis* / Q000235:genetics
keywords: amniocentesis; array comparative genomic hybridization; cytogenetic analysis; genetic counseling; trisomy 8 mosaicism