Cell-free DNA test for pathogenic copy number variations: A retrospective study.
OBJECTIVE
To evaluate the detection rate (DR) by prenatal cell-free DNA test for pathogenic copy number variations (CNVs)＞2 Mb among pregnancies with fetal ultrasound abnormalities.


MATERIALS AND METHODS
This was a retrospective study on 29 pregnant women with fetuses diagnosed as microdeletion/microduplication syndromes by prenatal chromosome microarray analysis (CMA). Cell-free DNA from the maternal plasma was sequenced on the NextSeq CN500 sequencer. The quality standard of unique map reads in a single sample was greater than 10 M and only gains and losses of more than 2 Mb were reported.


RESULTS
A total of 24 CNVs were identified by cell-free DNA test among the 21 fetuses with pathogenic CNVs identified by prenatal CMA, including 20 consistent CNVs and 4 inconsistent CNVs. Overall, the DR of cell-free DNA test for pathogenic CNVs ＞2 Mb was 69%. Microdeletions or microduplications at 22q11.2 were the most common CNVs, with a DR of 4/5 (80%) and 3/4 (75%) respectively.


CONCLUSION
Cell-free DNA test exhibited a moderate DR for pathogenic CNVs ＞2 Mb among fetuses with ultrasound abnormalities. Cell-free DNA test could provide an opportunity for early screening before the appearance of abnormalities on fetal ultrasound, while further clinical data and cost-effectiveness assessment are needed.
['Duan|Hong-Lei|HL|', 'Li|Jie|J|', 'Wang|Wan-Jun|WJ|', 'Cram|David S|DS|', 'Liu|Wei|W|', 'Cao|Pei-Xuan|PX|', 'Zhu|Xiang-Yu|XY|', 'Hu|Ya-Li|YL|']
Cell-free DNA Detection rate (DR) Microduplication syndromes Copy number variations (CNVs) Microdeletion syndromes