title: [Misdiagnosis of mosaic tetrasomy 9p in a fetus by single nucleotide polymorphism-based array].
abstract: OBJECTIVE
  To explore the reason for discordant results of karyotyping and microarray analysis in a fetus with mosaic tetrasomy 9p.
  
  
  METHODS
  Amniocentesis was carried out for a pregnant woman with advanced age for whom ultrasound scan has indicated fetal ventricular expansion, intrauterine growth retardation and persistent upper venous cavity. G-banded karyotyping and single nucleotide polymorphism-based arrays (SNP-array) analysis were performed at the same time.
  
  
  RESULTS
  Analysis of amniocytic chromosome has suggested mosaic tetrasomy 9p (47,XX,+psu idic(9)(q21)[23]/46,XX[27]). While SNP-array has detected a non-mosaic trisomy 9p with a 68.7 Mb duplication at 9p24.3q21.11. The results of the two methods were therefore discordant.
  
  
  CONCLUSIONS
  SNP-array will analyze genetic material in the form of numbers rather than morphology. For chimeras containing two types of cell lines, when the mosaic rate was close to 50% and the average amount of genetic material of the chimeras was equivalent to the amount of genetic material of non-chimeras, microarray analysis may come to the conclusion of a non-mosaic heteroploidy. Therefore, microarray results for large segment chromosome abnormalities should be combined with the results of G-banded karyotyping for genetic counseling.
authors.affiliation: Fetal Medicine Center, Department of Gynecology and Obstetrics, the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China. wujianzhu3140@126.com.
authors.forename: Jianzhu
authors.initials: J
authors.lastname: Wu
authors.forename: Yingjun
authors.initials: Y
authors.lastname: Xie
authors.forename: Baojiang
authors.initials: B
authors.lastname: Chen
mesh_terms: D000328:Adult; D000649:Amniocentesis / Q000379:methods; D000782:Aneuploidy; D002871:Chromosome Banding; D025063:Chromosome Disorders / Q000175:diagnosis / Q000235:genetics; D002899:Chromosomes, Human, Pair 9; D003951:Diagnostic Errors; D005260:Female; D005317:Fetal Growth Retardation / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D009030:Mosaicism; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D011256:Pregnancy Outcome; D014314:Trisomy