title: Determination of sensitivity and specificity of a novel gene dosage assay for prenatal screening of trisomy 21 syndrome.
abstract: OBJECTIVE
  To compare the gene dosage results achieved by a novel multiplex quantitative assay with cytogenetic and quantitative fluorescent polymerase chain reaction (QF-PCR) analysis for prenatal screening of trisomy 21 syndrome on corresponding fetal samples.
  
  
  METHODS
  Fetal samples (n=134) were collected from pregnant women considered high risk for having trisomy 21 affected fetus. Cytogenetic analysis and QF-PCR were performed. Then, the relative gene dosage of DSCAM and DYRK1A2 genes was determined on corresponding samples using comparative delta cycle of threshold (ΔC(T)) method.
  
  
  RESULTS
  The mean gene dosage ratio was 1.55 ± 0.11 (95% CI:1.51-1.58) in trisomy 21 cases and 1.01 ± 0.12 (95% CI:0.98-1.03) in normal samples (p value<0.001). The results were in agreement to the results of cytogenetic and QF-PCR analysis with the overall specificity of 0.96 (95% CI:0.91-0.98) and the sensitivity of 0.80 (95% CI:0.49-0.94).
  
  
  CONCLUSIONS
  This gene dosage assay is appropriate for the screening of high risk pregnant women and is readily amenable to automation.
authors.affiliation: Biotechnology Research Centre, Molecular Medicine Department, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Ahmad Reza
authors.initials: AR
authors.lastname: Kamyab
authors.forename: Fahimeh
authors.initials: F
authors.lastname: Shahrokhi
authors.forename: Elmira
authors.initials: E
authors.lastname: Shamsian
authors.forename: Mina
authors.initials: M
authors.lastname: Hayat Nosaied
authors.forename: Parvin
authors.initials: P
authors.lastname: Dibajnia
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Hashemi
authors.forename: Reza
authors.initials: R
authors.lastname: Mahdian
mesh_terms: D002891:Chromosomes, Human, Pair 21 / Q000235:genetics; D004314:Down Syndrome / Q000175:diagnosis* / Q000235:genetics*; D005260:Female; D005453:Fluorescence; D018628:Gene Dosage / Q000235:genetics*; D006801:Humans; D016014:Linear Models; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity