title: Diagnostic performance of quantitative fluorescence PCR analysis in high-risk pregnancies after combined first-trimester screening.
abstract: BACKGROUND
  We aimed to determine the diagnostic efficiency of quantitative fluorescence polymerase chain reaction (QF-PCR) in a clinical setting where most of the analyses are performed on chorion villus samples from high-risk pregnancies as determined by combined first-trimester screening.
  
  
  METHODS
  A retrospective study on QF-PCR data from all pregnancies in the Central and North Denmark Regions over a four-year period (n = 2,550) with invasive prenatal testing carried out due to a high risk of carrying a foetus with Down's syndrome. Results of QF-PCR were compared with those obtained by karyotyping. Other supplementary data were obtained from the Danish Foetal Medicine Database and the Danish Cytogenetic Central Register.
  
  
  RESULTS
  QF-PCR for common aneuploidies is fast, has a low failure rate, and is associated with high positive and negative predictive values (PPV, NPV) (> 99.8%) for all analysed abnormal karyotypes except for mosaicism for trisomy 13 (PPV = 20%) and sex chromosome mosaic cases (PPV = 40%; NPV = 99.7%)). In 25 (1%) cases, clinically significant chromosome abnormalities other than chromosomes 13, 18, 21, X, and Y were identified by karyotyping.
  
  
  CONCLUSIONS
  QF-PCR is a rapid and accurate diagnostic method to detect common aneuploidies in high-risk pregnancies. However, the rapid test cannot stand alone as several clinically significant abnormal karyotypes would be overlooked.
  
  
  BACKGROUND
  not relevant.
  
  
  BACKGROUND
  not relevant.
authors.affiliation: Klinisk Genetisk Afdeling, Aarhus Universitetshospital, Brendstrupgårdsvej 21 C, 8200 Aarhus N, Denmark. dolild@rm.dk.
authors.forename: Dorte Launholt
authors.initials: DL
authors.lastname: Lildballe
authors.forename: Ida
authors.initials: I
authors.lastname: Vogel
authors.forename: Olav Bjørn
authors.initials: OB
authors.lastname: Petersen
authors.forename: Else Marie
authors.initials: EM
authors.lastname: Vestergaard
mesh_terms: D000293:Adolescent; D000328:Adult; D000782:Aneuploidy; D025063:Chromosome Disorders / Q000175:diagnosis*; D002882:Chromosomes, Human, Pair 13; D002887:Chromosomes, Human, Pair 18; D003718:Denmark; D004314:Down Syndrome / Q000175:diagnosis; D005260:Female; D005453:Fluorescence; D006801:Humans; D007621:Karyotyping / Q000379:methods*; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood; D018566:Pregnancy, High-Risk; D011296:Prenatal Diagnosis / Q000379:methods*; D012189:Retrospective Studies; D025064:Sex Chromosome Disorders / Q000175:diagnosis; D014314:Trisomy / Q000175:diagnosis; D000073839:Trisomy 13 Syndrome; D000073842:Trisomy 18 Syndrome; D055815:Young Adult