C21ORF105, A chromosome 21-encoded mRNA, is nog a discriminative marker gene for prediction of Down sydrome in maternal plasma

Objectives: The presence and detectability of placental mRNA in maternal plasma opens possibilities for the development of non-invasive prenatal diagnostic tests. In this study, we tested C21orf105, a chromosome 2!-encoded, placentally expressed gene, in maternal plasma of women carrying a fetus with or without trisomy 21. Methods: Using real-time RT-PCR, we determined transcript levels of target (C21orf105) and reference (hPL) genes in first-trimester plasma samples. Plasma was obtained from first-trimester EDTA blood after two sequential centrifugation steps and stored at -70°C. After RNA extraction, quantitative RT-PCR was performed using Taqman probes. Results: From the 51 samples, 43 samples were conclusive. Comparison of transcript levels of C21orf105 in both groups showed no significant differences. When expressed as ratios of hPL/C21orf105, the differences between trisomy 21 and normal pregnancies remained non-significant. Conclusions: The amount of C21orf105 mRNA in maternal plasma, although situated in the Down syndrome critical region on chromosome 21 and up regulated in trisomy 21 placentas, is not higher in women carrying a fetus with trisomy 21. Copyright © 2006 John Wiley & Sons, Ltd.