Abstract
In this study we wanted to determine the performance of a paired-end sequencing-based
noninvasive prenatal testing (NIPT) assay in the detection of common fetal trisomies
in twin pregnancy samples. Samples from patients with a twin pregnancy were collected
from at least 10 weeks of gestation and analyzed at a single prenatal center in Germany.
Results of Anomaly Detected (i.e., high risk) or No Anomaly Detected (i.e., low risk)
for trisomy 21, trisomy 18, or trisomy 13 were reported. Follow-up confirmatory outcomes
were requested for all cases. A total of 1,658 patients with twin pregnancies submitted
samples during the study period; only two of these samples failed resulting in a low
failure rate of 0.12%. Of the remaining 1,656 cases, there were 1,625 (98.1%) low-risk
and 31 (1.9%) high-risk NIPT samples in our cohort. Of these, follow-up information
was available for 301 (18.5%) of the low-risk samples and 19 (61.3%) of the high-risk
samples. All of the low-risk cases with follow-up were determined to be true negatives
giving an estimated negative predictive value of 100%. Seventeen of the 19 high-risk
samples with follow-up were true positives, resulting in an overall positive predictive
value of 89.5%. Sensitivities of > 99.9% were noted for both trisomy 21 and trisomy
18, with high specificities of ≥ 99.7% observed for all three trisomies. In conclusion,
our study showed strong performance of the NIPT assay in the detection of common fetal
trisomies in twin pregnancy samples, with high sensitivities, specificities, and positive
predictive values observed based on known clinical outcomes along with a low failure
rate.
Keywords
noninvasive prenatal testing - twin pregnancy - trisomy - sensitivity - specificity
- positive predictive value
