Lab Breakout/Origin, Incidence and Outcomes: Piecing Together the Patterns of Mosaicism

Andrea Victor, PhD

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 0.75 CME

• Diving into embryonic mosaicism: discussing the biological origins of mosaicism and under what circumstances it may arise. Embryonic mosaicism is a biological phenomenon that has been described in pregnancies that have been achieved in-vivo and in-vitro. In the context of in-vitro mosaicism, there may be environmental factors that are more likely to induce this biological form. The current method used to detect in-vitro mosaicism from a clinical perspective prior to embryo implantation is by PGT-A. How valid is PGT-A at evaluating for embryonic mosaicism given its inherent limitations (biopsy and platform)? Mosaic embryos (as defined by PGT-A) do show distinct clinical outcome patterns when compared to embryos diagnosed as euploid by PGT-A. The most up-to-date data will be reviewed (results from >4,000 mosaic embryo transfers), including available prenatal testing results and delivery outcomes.

1. Origin of Mosaicism: To understand and review basic cell biology and the errors in cell division that can induce embryonic mosaicism.

2. Incidence of Mosaicism:Review existing literature that estimates the incidence of embryonic mosaicism in-vivo and in-vitro. Review mosaicism in the context of IVF and PGT-A. Review current literature suggesting mosaicism in the context of IVF/PGT can be a function of laboratory practices.

3. Outcomes of Mosaicism:Review up-to-date mosaic embryo transfer outcome data from IRMET (International Registry on Mosaic Embryo Transfers), including pregnancy rates, miscarriage rates, and prenatal testing results.

4. Understanding mechanisms by which mosaic embryos (in vivo and in vitro) can become healthy babies. (ie: not-mosaic merely artefact, self corrective mechanisms, etc).