Editing Prenatal testing (section)

== Prenatal genetic testing analysis techniques ==

=== Digital PCR ===
Recently{{When|date=December 2023}}, it has been proposed that digital [[polymerase chain reaction|PCR]] analysis can be conducted on fetal cell-free DNA for detection of fetal aneuploidy. Research has shown that digital PCR can be used to differentiate between normal and aneuploid DNA.<ref name="Ref4">{{cite journal |vauthors=Zimmermann BG, Grill S, Holzgreve W, Zhong XY, Jackson LG, Hahn S |date=December 2008 |title=Digital PCR: a powerful new tool for noninvasive prenatal diagnosis? |journal=Prenatal Diagnosis |volume=28 |issue=12 |pages=1087–93 |doi=10.1002/pd.2150 |pmid=19003785 |s2cid=2909830 |doi-access=free}}</ref>

A variation of the PCR technique called [[multiplex ligation-dependent probe amplification]] (MLPA), targeting DNA, has been successively applied for diagnosing fetal aneuploidy as a chromosome- or gene-specific assay.<ref name="Attie2011">{{cite journal |vauthors=Go AT, van Vugt JM, Oudejans CB |year=2010 |title=Non-invasive aneuploidy detection using free fetal DNA and RNA in maternal plasma: recent progress and future possibilities |journal=Human Reproduction Update |volume=17 |issue=3 |pages=372–82 |doi=10.1093/humupd/dmq054 |pmid=21076134 |doi-access=free}}</ref>

=== Shotgun sequencing ===
Fetal cell-free DNA has been directly sequenced using [[shotgun sequencing]] technology. In one study, DNA was obtained from the blood plasma of eighteen pregnant women. This was followed by mapping the chromosome using the quantification of fragments. This was done using advanced methods in [[DNA sequencing]] resulting in the parallel sequencing of the fetal DNA. The amount of sequence tags mapped to each chromosome was counted. If there was a surplus or deficiency in any of the chromosomes, this meant that there was a fetal aneuploid. Using this method of shotgun sequencing, the successful identification of trisomy 21 (Down syndrome), trisomy 18 (Edward syndrome), and trisomy 13 (Patau syndrome) was possible. This method of noninvasive diagnosis is now starting to be heavily used and researched further.<ref name="urlFetal DNA from Maternal Blood" />

=== Other techniques ===
Microarray analysis, karyotyping, and different genome sequencing techniques are also used to detect abnormalities. Fetal components in samples from maternal blood plasma can be analyzed by genome-wide techniques not only by total DNA, but also by [[methylated DNA]] immunoprecipitation (with tiling array), [[microRNA]] (such as with Megaplex) and total RNA ([[RNA-sequencing]]).<ref name="Attie2011" />