title: The detection of chromosome anomalies by QF-PCR and residual risks as compared to G-banded analysis.
abstract: OBJECTIVE
  To determine the detection rate of clinically significant chromosome abnormalities using quantitative fluorescent polymerase chain reaction (QF-PCR) of fetal DNA in comparison with G-banded analysis of cultured amniotic fluid cells and determine the residual risk if QF-PCR were performed alone for low-risk cases.
  
  
  METHODS
  Amniotic fluid samples were prospectively categorized based on the likelihood of the fetus having a chromosome anomaly. QF-PCR results were compared with the G-banded findings. The distribution of patients and the rates of clinically significant anomalies in each risk category were determined.
  
  
  RESULTS
  A total of 4176 amniotic fluid samples were studied. Among these, 331 cases with abnormalities were detected by both methods and an additional 19 abnormal cases were detected by G-banding only. Five of those undetected by QF-PCR were considered clinically significant, four of which were referred due to an elevated a priori risk (>4%). If QF-PCR is performed in all cases and G-banding performed only in higher risk cases, the residual risk for a clinically significant chromosome abnormality will be as low as 0.083%.
  
  
  CONCLUSIONS
  This study suggests that QF-PCR alone is appropriate for patients with uncomplicated pregnancies, who are referred solely for an increased risk of a common trisomy.
authors.affiliation: Credit Valley Hospital, Mississauga, Ontario, Canada. mspeevak@cvh.on.ca
authors.forename: Marsha D
authors.initials: MD
authors.lastname: Speevak
authors.forename: Jean
authors.initials: J
authors.lastname: McGowan-Jordan
authors.forename: Kathy
authors.initials: K
authors.lastname: Chun
mesh_terms: D000328:Adult; D000649:Amniocentesis / Q000379:methods; D000653:Amniotic Fluid / Q000166:cytology; D002170:Canada / Q000453:epidemiology; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D002871:Chromosome Banding / Q000379:methods*; D025063:Chromosome Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D011237:Predictive Value of Tests; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D011446:Prospective Studies; D012017:Referral and Consultation; D012307:Risk Factors