Determination of sensitivity and specificity of a novel gene dosage assay for prenatal screening of trisomy 21 syndrome

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. 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 (ΔCT) method. 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