Prenatal Diagnosis of Paternal Uniparental Isodisomy 14 Arising From the Transfer of a Mosaic Monosomy 14 Embryo.

The practice of transferring PGT-A (preimplantation genetic testing for aneuploidy) "mosaic" embryos has become increasingly common, yet there is limited data on the genetic outcomes of these transfers. We herein present a case of fetal paternal uniparental isodisomy of chromosome 14 arising from an embryo categorized as high-level mosaic for monosomy 14. To our knowledge, this case represents the first reported case of uniparental isodisomy following the transfer of a mosaic embryo. This case demonstrates the clinical risk of uniparental disomy after mosaic embryo transfer, adding to a growing body of evidence. This case also emphasizes the need for clear guidelines regarding prenatal diagnostic testing following the transfer of mosaic embryos, and highlights the essential role of prenatal genetics specialists in providing targeted counseling and care for these patients.