Comparative genomics analysis of aneuploidy and cellular fragmentation dynamics in mammalian embryos

One of the main causes of implantation failure and spontaneous miscarriage in natural pregnancies and following in vitro fertilization is whole chromosomal losses and gains, or aneuploidy. While ∼50-80% of cleavage-stage human embryos contain at least one aneuploid cell, estimates of aneuploidy in other mammals vary between ∼4 and ∼85%. Cellular fragmentation (CF), the dynamic process by which cytoplasmic bodies pinch off blastomeres during cytokinesis, is often associated with aneuploidy and has been observed in both in vitro and in vivo-derived embryos from several mammals, albeit to similarly varying degrees. Why the prevalence of aneuploidy and CF vary across species is unknown and this is mostly because the underlying molecular factors are not fully understood. The overall goal of this study was to leverage the natural diversity of embryo aneuploidy and CF frequency in mammals and identify the molecular mechanisms mediating these processes using high resolution sequencing and imaging approaches.