Combined application of copy number variation sequencing and chromosomal karyotype analysis in prenatal diagnosis of birth defect

  Objective  To evaluate the significance of next generation sequencing technology-based copy number variation sequencing (CNV-seq) combined with chromosomal karyotype analysis in prenatal diagnosis of birth defect.

  Methods  With convenient sampling, we recruited 516 singleton pregnant women undergoing prenatal amniocentesis examination at a hospital in Shenyang city from January 1, 2017 to December 31, 2018. The chromosomes of exfoliated cells in amniotic fluid samples were examined with CNV-seq and routine G-banded karyotype analysis.

  Results  Among all specimens negative for chromosome copy number variations (CNVs) in chromosomal karyotype analysis, 30 specimens positive for CNVs were detected with CNV-seq and specific variation sites of abnormal chromosome structure were also detected with CNV-seq in 13 abnormal specimens in chromosomal karyotype analysis; in addition, 5 specimens with a chimera ratio of > 10% were identified with CNV-seq. But one specimens with a chimera ratio of < 1% and 13 specimens with abnormal chromosomal structure in karyotype analysis were not detected with CNV-seq.

  Conclusion  Copy number variation sequencing can improve low resolution of chromosomal karyotype analysis and detection rate of abnormal chromosomes and the detection could be applied in prenatal amniotic fluid diagnosis of birth defect.