高通量测序全基因组拷贝数变异检测技术在高危孕妇产前诊断中的应用价值

Application value of high-throughput sequencing technique for the detection of whole genome copy number variations in prenatal diagnosis of high-risk pregnant women

目的:通过比较羊水细胞高通量测序(又称下一代测序)全基因组拷贝数变异(NGS-CNVs)和染色体核型分析,探讨NGS-CNVs技术在产前诊断中的实际应用价值。方法:选取2017年1月至2019年12月在我院有产前诊断指征的孕妇为研究对象。无菌羊膜腔穿刺术后行羊水细胞染色体核型分析和NGS-CNVs技术筛查,通过比较来验证NGS-CNVs技术在产前诊断中的可行性。结果:在201例羊水标本中,除了两种方法共同发现的6例(2.99%)染色体数目异常和1例(0.50%)结构异常外,NGS-CNVs技术还筛查出2例致病性CNVs、6例多态性CNVs和6例临床意义不明CNVs,而染色体核型分析均未查出相应的染色体异常;染色体核型分析还发现7例平衡易位、5例臂间倒位和6例染色体多态性等异常,而NGS-CNVs技术未筛查出相应的染色体CNVs变化。NGS-CNVs技术筛查异常染色体的检出率略低于染色体核型分析,但McNemar检验分析提示两种方法诊断染色体异常具有一致性(P=0.597)。结论:NGS-CNVs技术有助于弥补染色体核型分析技术低分辨率的缺陷,提高产前遗传学检查的水平和降低新生儿出生缺陷,但不能完全替代染色体核型分析。

Objective:To explore the practical application value of high-throughput sequencing(also known as next generation sequencing)whole genome copy number variations(NGS-CNVs)in prenatal diagnosis in comparison with chromosomal karyotype analysis of amniotic fluid cells.Methods:From January 2017 to December 2019,pregnant women with indications of prenatal diagnosis in our hospital were recruited.Amniotic fluid samples were obtained by aseptic amniocentesis and then amniotic fluid cells were collected to perform the NGS-CNVs and chromosome karyotype analysis,thereby verifying the feasibility of NGS-CNVs in prenatal diagnosis.Results:Among201 amniotic fluid samples,6 cases(2.99%)of abnormal chromosome number and 1 case(0.50%)of abnormal chromosome structure were detected by two methods.NGS-CNVs technology also verified another 2 cases of pathogenic CNVs,6 cases of polymorphism and 6 cases of clinically unknown CNVs,while no chromosomal abnormalities in the corresponding amniotic fluid cells were detected by chromosome karyotype analysis.Simultaneously,chromosome karyotype analysis also revealed another 7 cases of balanced translocation,5 cases of interarm inversion and 6 cases of chromosome polymorphism,but no changes of CNVs in the corresponding amniotic fluid cells were detected by NGS-CNVs technology.Although the rate of abnormal chromosomes detected by NGS-CNVs technology was slightly lower than that by chromosome karyotype analysis,Mc Nemar statistical analysis showed that the two methods were consistent in the diagnosis of chromosomal abnormalities(P=0.597).Conclusion:NGS-CNVs technique is helpful to make up for the defects in the low resolution of chromosome karyotype analysis,improve the level of prenatal genetic examination and reduce birth defects,but it cannot completely replace chromosome karyotype analysis.