Nationwide demonstration project of next-generation sequencing of cell-free DNA in maternal plasma in Japan: 1-year experience

Objective: To report the 1-year experience of a nationwide demonstration project to introduce noninvasive prenatal testing of aneuploidy from maternal plasma and discuss how to implement this program in Japan. Methods: The test was conducted to detect aneuploidy in high-risk pregnant women with adequate genetic counseling. The clinical data, test results, and pregnancy outcomes were recorded. Results: Of the 7740 women tested, 142 (1.8%) had positive results, 7594 (98.1%) had negative results, and four (0.1%) had results that were not reportable. Of the 142 women who tested positive, 13 cases resulted in intrauterine fetal death, and three cases refused to undergo the invasive procedure. Of the 126 positive cases confirmed on karyotyping, a normal karyotype was observed for trisomy 21 in three cases, trisomy 18 in eight cases, and trisomy 13 in two cases. In the follow-up study of the negative cases (n=1638), only one false-negative case of trisomy 18 was detected. Conclusions: We described our nationwide 1-year experience with noninvasive prenatal genetic testing. It is expected that the present data will stimulate a debate regarding prenatal genetic testing and hopefully lead to improvements in the perinatal care system with respect to genetic counseling in Japan.