Molecular genetic analysis reveals atypical confined placental mosaicism with a small supernumerary marker chromosome derived from chromosome 18: A clinical report of discordant results from three prenatal tests

We present a case with discordant results in three prenatal screening methods, with additional genetic analyses. Non-invasive prenatal testing (NIPT) was performed on a 41-year-old Japanese woman at 10 weeks of gestation, and the result was positive for trisomy 18 with high accuracy. Amniocentesis was performed at 16 weeks of gestation. However, the result showed 47,XX,+mar[16]/47,XX,+18[2]. Fetal examination by ultrasound revealed no...