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Embryo Mosaicism: What You Need to Know

by Dr. Geoffrey Sher on June 28, 2017

In 2005, my associate Levent Keskintepe PhD and I introduced Preimplantation Genetic Screening (PGS) with the ability to identify all chromosomes in the embryo’s cells, into the field of IVF.

This approach, which is now widely used throughout the world, permits selection of those embryos that are most likely to be competent, and has dramatically improved IVF success rates.

However, some abnormal (or aneuploid) embryos are capable of autocorrecting and reverting to a normal karyotype (euploid) during intrauterine development and of then propagating healthy babies. This is because some embryos can harbor both aneuploid AND euploid cells. This combination of aneuploid plus euploid cells in the same embryo is referred to as “mosaicism.”

It is an indisputable fact that many mosaic embryos further cell replication can result in the euploid cell component predominating ultimately resulting in a healthy conceptus. In many cases it is not possible to identify embryo “mosaicism”. Accordingly, we tend to preserve certain aneuploid embryos and recommend that they be transferred.

Once pregnant chorionic villus sampling (CVS) or amniocentesis should be done to determine the normalcy of the pregnancy, providing the patient(s) with the opportunity to terminate such pregnancies if they so choose. Join me tomorrow at 1:00PM PST on my Facebook page, as I address the pros and cons of preserving versus discarding all aneuploid embryos and define my policy in advising such patients.

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  • Brianna - June 29, 2017 reply

    What are your thoughts/opinions on transferring an XXY or an XYY embryo? Thanks!

    Dr. Geoffrey Sher

    Dr. Geoffrey Sher - June 29, 2017 reply

    I would not knowingly do so!

    Geoff Sher

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