低深度全基因组拷贝数变异测序在复发性流产遗传学诊断中的应用

Low-depth whole genome copy number variation sequencing for genetic diagnosis of recurrent abortion

目的:探讨基于高通量测序技术的低深度全基因组测序技术在复发性流产胚胎或绒毛组织染色体异常的应用价值。方法:选择2019年3月—2021年8月就诊于汕头大学医学院第一附属医院妇产科门诊并确诊为自然流产的患者,孕周为5~16周,留取流产组织,提取DNA,制备文库,进行流产物染色体低深度全基因组拷贝数变异测序,分析胚胎染色体数目和结构变异结果。结果:197例样本检测全部成功,检出染色体异常样本135例,染色体异常检出率为68.5%,其中检出染色体数目异常104例(77.0%),染色体部分重复/缺失26例(19.3%),染色体数目异常合并部分重复/缺失5例(3.7%),嵌合体10例(7.4%);染色体数目异常以16 (11.85%)、X (9.63%)、22 (96.67%)、21 (5.93%)染色体高发。≥35岁患者的染色体数目异常率比<35岁患者的高(分别为70.0%和51.6%,P<0.05)。共检出26例染色体部分重复/缺失,最短序列长度为0.12 Mb,最大片段94.54 Mb。在26例CNVs中,9例CNVs有明确致病性,2例CNVs提示可能致病。其中4个包含微缺失/微重复综合征。结论:低深度全基因组拷贝数变异测序技术能有效检测出流产胚胎绒毛组织染色体的非整倍体和部分重复/缺失情况,有助于明确复发性流产的病因,指导患者优生优育。

Objective:To explore the value of low-depth whole genome sequencing based on high-throughput sequencing technology in the application of chromosomal abnormalities in embryonic or chorionic tissue in recurrent miscarriage.Methods:Patients who attended the obstetrics and gynecology clinic of the First Affiliated Hospital of Shantou University Medical College from March 2019 to August 2021 and were diagnosed with spontaneous miscarriage at 5-16 weeks of gestation were selected to retain miscarriage tissues,extract DNA,prepare libraries,perform low-depth whole-genome copy number variation sequencing of chromosomes of miscarriage products,and analyze embryonic chromosome number and structural variation results.Results:All 197 samples were successfully tested,135 chromosomal abnormalities were detected,and the detection rate of chromosomal abnormalities was 68.5%,including 104 cases of chromosomal number abnormalities(77.0%),26 cases of partial duplications/deletions(19.3%),5 cases of chromosomal number abnormalities combined with partial duplications/deletions(3.7%),and 10 cases of chimerism(7.4%);chromosome number abnormalities were high for chromosomes 16(11.85%),X(9.63%),22(96.67%),and 21(5.93%).The prevalence of chromosome number abnormalities was high with 16(11.85%),X(9.63%),22(96.67%)and 21(5.93%)chromosomes.The rate of chromosome number abnormalities was higher in patients≥35 years old than in patients<35 years old(70.0%and 51.6%,P<0.05).A total of 26 cases of partial chromosome duplication/deletion were detected among them,with the shortest sequence length of 0.12 Mb and the largest fragment of 94.54 Mb.Among the 26 CNVs,9 CNVs were clearly pathogenic and 2 CNVs suggested possible pathogenicity.Four of them contained microdeletion/microduplication syndromes.Conclusion:Low depth whole genome copy number variant sequencing technology can effectively detect aneuploidy and partial duplication/deletion of chromosomes in the chorionic tissue of miscarried embryos,which can help to clarify the etiology of recurrent miscarriage and guide patients to eugenics.