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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. Design and 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 (ΔCT) 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. [Copyright &y& Elsevier]

Objective: Rapid diagnosis of Trisomy 21 Syndrome (Down Syndrome) patients using Real-Time quantitative Polymerase Chain Reaction (Real-Time qPCR) in order to establish a novel method for prenatal diagnosis in the future. Materials and Methods: A total of 5 ml of peripheral blood was obtained from each patient and normal controls (NR). Then, genomic DNA from lymphocytes was extracted using the salting out procedure. Gene dosage levels of DSCAM and (PMP22, DSCAM) in Down Syndrome and NR were analyzed using real-time quantitative PCR. The DSCAM/ PMP22 ratio was calculated according to the 2-ΔΔCt formula for all samples. Results: Real-time PCR showed a DSCAM/PMP22 ratio of 1.48 ± 0.18 and 1.01 ± 0.10 (p<0.001) in Down Syndrome and normal samples, respectively, demonstrating three copies of the target (DSCAM) gene in Trisomy 21 Syndrome. Conclusion: DSCAM/PMP22 ratio is increased significantly in Down Syndrome patients than NR (1.5 times). Therefore, the real-time quantitative PCR technique can be used as a sensitive, accurate and reliable technique for rapid and prenatal diagnosis of Trisomy 21 Syndrome. [ABSTRACT FROM AUTHOR]