Amber Gamma

Genetic Counseling, Northwell Health Fertility
  • Northwell Health Fertility
  • United States of America

Recent Comments

Feb 04, 2019

Very excited to see this data published; however I would like to note that NIPT is not the most appropriate follow-up test for women who become pregnant from a mosaic embryo and found its inclusion in the data as proof of a good/"normal" outcome puzzling. Firstly, NIPT is a screening test that uses cell-free fetal DNA, which is placental in origin and therefore arises from the trophectoderm of the embryo. While concordant with the fetus in most cases, it may be normal in the presence of a chromosomally abnormal fetus and is particularly problematic if confined placental mosaicism exists. Second, most NIPT platforms include only chromosomes 13, 18, 21 and the sex chromosomes and therefore give you no information on other chromosome aneuploidies that may have been mosaic in the embryo on PGT-A. Finally, while a whole-genome NIPT is currently available, there remain a lot of unknowns about the performance of this screening test in terms of its positive predictive value (PPV) and negative predictive values (NPV). False-positives are likely on this testing, which would push a patient with a very precious pregnancy to diagnostic testing through CVS or amniocentesis. Amniocentesis remains the optimal follow-up test for patients who become pregnant (with 50 cell karyotype and microarray if a segmental mosaic was transferred!). NIPT must be offered with care and proper counseling regarding the limitations. Thanks for this exciting paper!