Isn’t it time to stop calling preimplantation embryos “mosaic”?

Isn’t it time to stop calling preimplantation embryos “mosaic”?

VOLUME 1, ISSUE 3, P164-165, DECEMBER 01, 2020


Richard J. Paulson, M.D., M.S., Nathan R. Treff, Ph.D., H.C.L.D.


This August, the long-awaited Practice Committee opinion on the management of mosaic results from preimplantation genetic testing for aneuploidies (PGT-A) was published (1). It is an impressive body of work that will be helpful to clinicians and patients who are dealing with the difficult decision of which embryos to transfer. The opinion is overall very well balanced and carefully written. However, the authors stopped short of calling for the abandonment of the term, “mosaic” when referring to “intermediate copy number” of individual chromosomes. The latter term is more accurate, and we propose that it should be used in place of the inaccurate and, arguably, misleading term “mosaic.”

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