Abstract
BackgroundWe investigated fetal and total DNA levels in maternal plasma in patients bearing fetuses affected with Down syndrome in comparison to controls carrying fetuses with normal karyotype.MethodsDNA levels in maternal plasma were measured using real-time quantitative PCR using SRY and β-globin genes as markers. Twenty-one pregnant women with a singleton fetus at a gestational age ranging from 15 to 19 weeks recruited before amniocentesis (carried out for reasons including material serum screening and advanced material age), and 16 pregnant women bearing fetuses affected with Down syndrome between 17 to 22 weeks of gestation were involved in the study.ResultsThe specificity of the system reaches 100% (no Y signal was detected in 14 women pregnant with female fetuses) and the sensitivity 91.7% (SRY amplification in 22 of 24 examined samples). The median fetal DNA levels in women carrying Down syndrome (n=11) and the controls (n=13) were 23.3 (range 0–58.5) genome-equivalents/ml and 24.5 (range 0–47.5) genome-equivalents/ml of maternal plasma, respectively (P = 0.62). The total median DNA levels in pregnancies with Down syndrome and the controls were 10165 (range 615–65000) genome-equivalents/ml and 7330 (range 1300–36750) genome-equivalents/ml, respectively (P = 0.32). The fetal DNA proportion in maternal plasma was 0%-6 % (mean 0.8%) in women carrying Down syndrome and 0%-2.6 % (mean 0.7 %) in the controls, respectively (P=0.86).ConclusionsOur study revealed no difference in fetal DNA levels and fetal DNA: maternal DNA ratio between the patients carrying Down syndrome fetuses and the controls.
Highlights
We investigated fetal and total DNA levels in maternal plasma in patients bearing fetuses affected with Down syndrome in comparison to controls carrying fetuses with normal karyotype
The median fetal DNA levels in maternal plasma obtained from women carrying Down syndrome (n = 11) and the controls carrying fetuses with normal karyotype (n = 13) were 23,3 genome-equivalents/ml and 24,5 genome-equivalents/ml
The fetal DNA proportion in maternal plasma was 0 % – 6 % in women carrying Down syndrome and 0%–2,6 % in the controls carrying fetuses with normal karyotype, respectively (P = 0.86)
Summary
We investigated fetal and total DNA levels in maternal plasma in patients bearing fetuses affected with Down syndrome in comparison to controls carrying fetuses with normal karyotype. Current experimental non-invasive methods for the prenatal diagnosis of fetal genetic characteristics use free extracellular fetal DNA and fetal cells isolated from maternal peripheral blood. Free extracellular fetal DNA which can be detected by polymerase chain reaction (PCR) in the serum or plasma of pregnant women [1] has been previously successfully used for the prenatal diagnosis of fetal sex and rhesus D status [2,3,4,5]. We investigated the fetal and total DNA levels in maternal plasma in patients bearing fetuses affected with Down syndrome in comparison to the controls carrying fetuses with normal karyotype. The detection of Y DNA was used in male fetuses because a generic fetal DNA marker is not yet available
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