Soler N, Bautista-Llàcer R, Escrich L, et al. - In this prospective experimental study, researchers sought to measure the percentage of monopronuclear-derived blastocysts (MNBs) that are potentially useful for reproductive purposes using classic and state-of-the-art chromosome analysis approaches, as well as to analyze chromosomal distribution in the inner cell mass (ICM) and trophectoderm (TE) for intertissue/intratissue concordance comparison. Between June 2016 and December 2018, 1,128 monopronuclear zygotes were obtained. In a single biopsy, the a-SNP-trio strategy gives data about ploidy, euploidy, and parental origin. This method allowed us to identify 40% of MNBs with reproductive potential, which can have a significant impact in the clinical setting. Furthermore, segmental aneuploidy is important for mismatched preimplantation genetic testing of aneuploidies within and between MNB tissues. A repeat biopsy may reveal whether segmental aneuploidy is a prone genetic character.