Screening of fetal chromosomal aneuploidy diseases using noninvasive prenatal testing in twin pregnancies

<b>Objectives</b>: This study was aimed to report the clinical characteristics of fetal chromosomal aneuploidy diseases using noninvasive prenatal testing (NIPT) in twin pregnancies and analyze the results in terms of chorionicity, conception, and fetal fraction. <b>Methods</b>: A total of 1160 women with twin pregnancies were recruited from 1 October 2015, to 1 August 2017. Next-generation sequencing technology was used to detect fetal aneuploidies, such as trisomy 21, trisomy 18, trisomy 13 and trisomy X. <b>Results</b>: Aneuploidy was detected using NIPT in 26 fetuses, among which 18 fetal aneuploidies occurred in only one fetus of the twins. The rate of aneuploidy was 1.3% for dichorionic diamniotic twins and 0.5% for monochorionic diamniotic twins, respectively. The rate of aneuploidy was 1.2% for spontaneous pregnancy group and 1.1% for assisted reproductive technologies group. <b>Conclusion</b>: In this study, detection of trisomy 21, trisomy 18, trisomy 13, and X abnormality in twin pregnancies was confirmed to be accurate. The aneuploidies mostly occurred in only one fetus of the twins, and trisomy 21 was the most common type. The prenatal diagnostic standard for NIPT in singleton pregnancies could perform well in twin pregnancies, which means NIPT can be popularized as routine prenatal screening in twin pregnancies.

## 研究目的
本研究旨在报告双胎妊娠孕妇接受无创产前检测（noninvasive prenatal testing, NIPT）时检出的胎儿染色体非整倍体疾病的临床特征，并从绒毛膜性、受孕方式及胎儿分数三个维度对检测结果进行分析。
## 研究方法
本研究于2015年10月1日至2017年8月1日期间，共纳入1160例双胎妊娠孕妇。采用下一代测序技术（next-generation sequencing, NGS）检测胎儿染色体非整倍体，包括21-三体、18-三体、13-三体及X染色体三体。
## 研究结果
本研究通过NIPT共检出26例胎儿染色体非整倍体，其中18例仅累及双胎中的单个胎儿。双绒毛膜双羊膜囊（dichorionic diamniotic, DCDA）双胎的非整倍体检出率为1.3%，单绒毛膜双羊膜囊（monochorionic diamniotic, MCDA）双胎的检出率为0.5%。自然受孕组的非整倍体检出率为1.2%，辅助生殖技术（assisted reproductive technologies, ART）组的检出率为1.1%。
## 研究结论
本研究证实，针对双胎妊娠的21-三体、18-三体、13-三体及X染色体异常的NIPT检测结果准确可靠。胎儿染色体非整倍体多仅累及双胎中的单个胎儿，其中以21-三体最为常见。单胎妊娠所采用的NIPT产前诊断标准可良好适用于双胎妊娠，提示NIPT可作为双胎妊娠的常规产前筛查手段进行推广应用。