Editing Prenatal testing (section)

=== 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" />