Background: Placental mosaicism is one of the major reasons for noninvasive prenatal testing (NIPT) discrepancy. Herein, we discovered a rare case of placenta with complex karyotypes that caused false-positive and false-negative results in noninvasive prenatal testing.
Methods: Next-generation sequencing (NGS) and Quantitative fluorescent polymerase chain reaction (QF-PCR) were performed on the cord blood sample, fetal tissues, and eight placental biopsies. Fluorescent In Situ Hybridization (FISH) and karyotyping were also carried to confirm the fetal genome status.
Results: The results suggested that the fetal chromosome was 47,XXX and the placenta had three karyotypes of 48,XXX,+21, 47,XX,+21, and 47,XXX. QF-PCR indicated that the extra chromosome 21 and chromosome X were all from the father. It is speculated that the zygote may have 48,XXX,+21 karyotype and trisomy rescue could be the main mechanism for the development of the homogeneous fetus and complex mosaic placenta.
Conclusion: Overall, the complicated nature of our case underlines the importance of discussing with parents the possibility of both atypical and discordant results during preconfirmatory amniocentesis counseling and consent.
Keywords: NIPT; chromosomal abnormalities; confined placental mosaicism; prenatal diagnosis; trisomy.
© 2020 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.