Noninvasive prenatal testing of trisomies 21 and 18 by massively parallel sequencing of maternal plasma DNA in twin pregnancies

Abstract

Objective The objective of this study is to assess the performance of noninvasive prenatal testing for trisomies 21 and 18 on the basis of massively parallel sequencing of cell-free DNA from maternal plasma in twin pregnancies.Method A double-blind study was performed over 12 months. A total of 189 pregnant women carrying twins were recruited from seven hospitals. Maternal plasma DNA sequencing was performed to detect trisomies 21 and 18. The fetal karyotype was used as gold standard to estimate the sensitivity and specificity of sequencing-based noninvasive prenatal test.Results There were nine cases of trisomy 21 and two cases of trisomy 18 confirmed by karyotyping. Plasma DNA sequencing correctly identified nine cases of trisomy 21 and one case of trisomy 18. The discordant case of trisomy 18 was an unusual case of monozygotic twin with discordant fetal karyotype (one normal and the other trisomy 18). The sensitivity and specificity of maternal plasma DNA sequencing for fetal trisomy 21 were both 100% and for fetal trisomy 18 were 50% and 100%, respectively. ConclusionOur study further supported that sequencing-based noninvasive prenatal testing of trisomy 21 in twin pregnancies could be achieved with a high accuracy, which could effectively avoid almost 95% of invasive prenatal diagnosis procedures.

Noninvasive prenatal testing (NIPT) in twin pregnancies with treatment of assisted reproductive techniques (ART) in a single center

“…Lau et al also showed 100% sensitivity and specificity of NIPT in 12 twin pregnancies, including four IVF conceptions and four conceptions via intra‐uterine insemination or ovulation induction . In a larger study of 189 twin pregnancies with karyotyping results, 113 were conceptions via ART, and NIPT identified all nine cases of T21 and one out of two cases of T18 . In another study involving 351 twin pregnancies with known outcomes, 11 in total of 12 T21 cases and 5 T18 cases were correctly identified by NIPT .…”

“…Plasma was prepared within 4 h after blood collection using a two‐step centrifugation, and then sent to the Minister of Health accredited and ISO/IEC17025‐certified clinical laboratories of BGI‐Shenzhen, China. Plasma DNA extraction, library preparation for sequencing, and NIPT using massively parallel sequencing have been described before . Fetal aneuploidy risk was evaluated using a binary hypothesis t ‐test and logarithmic likelihood ratio L ‐score.…”

“…Several previous studies showed high sensitivity and specificity of NIPT in detecting common fetal aneuploidies in singleton pregnancies . Sporadic evidence also showed the possibility of using NIPT in ART twin pregnancies . However, large prospective analysis of NIPT in ART twin pregnancies has not been reported.…”

Noninvasive Prenatal Screening for Genetic Diseases Using Massively Parallel Sequencing of Maternal Plasma DNA

“…For the majority of studies, NIPT is performed variably from the first to the third trimester when the levels of cffDNA may be higher and performance of NIPT improved. There are fewer data available in multiple pregnancies, with reports largely being based on stored plasma samples (del Mar Gil et al 2014) or small prospective studies (Canick et al 2012;Lau et al 2012;Huang et al 2014). However, a meta-analysis of studies determined a detection rate of 94.4% for trisomy 21 (95% CI 74.2 -99.0) in twin pregnancies ) and most commercial companies now offer testing in multiple pregnancies.…”

Clinical Perspective of Cell-Free DNA Testing for Fetal Aneuploidies

“…A few studies on a small number of patients have shown that the performance cfDNA testing is high also in twin pregnancies [28,29,30]. …”