Application of Copy Number Variation Sequencing Technology in 422 Foetuses with Abnormal Ultrasound Soft Markers.

Purpose: The application value of ultrasound soft indicators in prenatal diagnosis was evaluated by copy number variation sequencing (CNV-seq).

Methods: The authors conducted a retrospective analysis of 422 pregnant women who underwent CNV-seq testing at Luoyang Maternal and Child Health Hospital between January 2020 and November 2021. The women had presented with abnormal ultrasound soft markers; those identified as high-risk through non-invasive prenatal screening were excluded.

Results: A total of 43 abnormal cases were detected in 422 pregnant women, including 24 aneuploidy (including chimerism) and 19 pathogenic or likely pathogenic copy number variations (CNVs). Based on the characteristics of ultrasound soft indicators, pregnant women were divided into five groups: isolated nuchal translucency (NT) group, combined NT group, isolated soft indicators group, combined soft indicators group and combined non-NT group. The abnormality detection rates in the five groups were 12.38% (13/105), 36.11% (13/36), 3.74% (4/103), 3.08% (2/63) and 10.09% (11/109), respectively. Statistical tests showed that the detection rate in the NT thickening combined with other abnormalities group was significantly higher than the other four groups, while there was no statistical difference in the detection rate among the other four groups.

Conclusion: When NT thickening is combined with other abnormalities, it is more likely to indicate chromosome abnormalities or CNVs, so it should be regarded seriously upon finding, and pregnant women should be referred for prenatal diagnosis according to the examination results. In addition, NT thickening is an important indicator for prenatal diagnosis and should be considered regardless of whether it occurs independently. The authors recommend CNV-seq for prenatal diagnosis to prevent missing small fragments of CNVs during traditional karyotyping.