Clinical application of chromosomal karyotyping combined with copy number variation sequencing in prenatal diagnosis of high-risk pregnan-cies
Objective This study explored the application value of chromosomal karyotyping combined with copy number variation sequencing(CNV-seq)in prenatal diagnosis.Methods A total of 976 singleton pregnant women with high risk of fetal chromosomal abnormalities who visited the Southwest Medical University Hospital for amniocentesis from July 2022 to June 2023 were studied.Amniotic fluid samples were subjected to chromosome karyotyping and CNV-seq,and the detection rates of abnormalities were compared between techniques.Results In the 976 amniotic samples,the abnormality detection rate with chromosomal karyotype analysis was 4.30％(42/976),and that with low-depth whole genome sequencing was 10.35％(101/976).CNV-seq detected 66 more cases of chromosome copy number variations(CNVs)than chromosomal karyotyping.Of these,20 cases were pathogenic copy number variations(pCNVs).Chromosomal karyotype analysis detected six cases of abnormally balanced structure and one case of chimerism not detected by CNV-seq.Combined use of both tech-niques detected abnormalities in 108 cases,with an abnor-mality rate of 11.07％.Statistically significant differences were observed in the abnormal detection rates among karyo-typing,CNV-seq,and karyotyping combined with CNV-seq(x2=34.364,P＜0.001).The abnormality detection rate was lower with karyotyping than CNV-seq and combined test-ing,and the differences were statistically significant(x2=26.267,31.457,both P＜0.001).Conclusions The combined application of karyotyping and CNV-seq is valuable in improv-ing the detection rate of chromosomal microdeletion/microduplication.The combined use of these two techniques has particu-larly high clinical value when one or both spouses are carriers of balanced karyotype changes.
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