Advances in the research of fetal DNA in maternal plasma for noninvasive prenatal diagnostics.

Molecular analysis of fetal DNA present in the maternal circulation allows noninvasive, early, and precise determination of fetal genetic status in prenatal diagnostics. The most common clinical applications, i.e. prenatal gender determination and fetal RhD genotyping, are possible already in the first trimester using specialized protocols for DNA isolation from plasma and subsequent real-time PCR detection. Recent advances in molecular techniques enable other applications of fetal DNA purified from maternal plasma samples. Chromosomal abnormalities (e.g. trisomy 21) can be diagnosed by digital PCR, which offers higher accuracy in quantifying DNA sequences than standard real-time PCR. Digital PCR, but also MALDI-TOF, are suitable for detecting point mutations, widening the spectrum of applications to monogenic diseases. The ongoing lowering of costs for massively parallel sequencing might lead to replacement of most of the other currently used approaches. Adopting specialized protocols for the purification of fragmented circulating fetal DNA and improving the bioinformatic analysis of raw data can bring us closer to sequencing the fetal genome as the ultimate goal of prenatal DNA diagnostics, with wide-ranging medical applications. The discussion and solution of ethical issues beyond early fetal gender or paternity determination is hanging just behind the rapid technical progress of noninvasive prenatal DNA diagnostics.