Abstract:

Objective To analyze amniotic fluid chromosome karyotype and genome copy number variation in critical or high-risk pregnant women by Down's screening，and to provide a reference for prenatal diagnosis of critical or high-risk pregnant women. Methods A total of 450 critical or high-risk pregnant women by Down's screening in Fuyang People's Hospital from December 2019 to October 2021 were enrolled. All of them underwent amniocentesis，and chromosomal karyotype and chromosomal microarray analysis（CMA） or genome copy number variation sequencing（CNV-seq） were performed. Results Chromosomal karyotype analysis detected 40 abnormal karyotypes，accounting for 8.89%，including 29（6.44%） cases of trisomy 18/21-syndrome，11（2.44%） cases of non-trisomy 18/21 chromosome abnormalities [3（0.67%） cases of autosome abnormalities and 8（1.78%） cases of sex chromosome abnormalities]. A total of 76 cases of chromosomal abnormalities were detected by CMA or CNV-seq，of which 35 cases were consistent with karyotype analysis and 41 were inconsistent [including 2 cases of balanced chromosomal translocation，2 cases of complex sex chromosome structure chimerism，12 cases of pathogenic and suspected pathogenic copy number variation（CNV） and 25 cases of unknown clinical significance]. A total of 23（5.11%） cases of non-trisomy 18/21 chromosome abnormalities were detected by chromosomal karyotype analysis combined with copy number variation. Conclusions In addition to trisomy 18/21-syndrome，the critical or high-risk of Down's screening can also be used to indicate the chromosome abnormalities of non-trisomy 18/21. The amniotic fluid chromosomal karyotype analysis combined with CMA or CNV-seq in prenatal diagnosis can improve the detection rate of chromosome abnormalities.

Key words: Down's screening, Prenatal diagnosis, Chromosomal karyotype analysis, Copy number variation