Here, we report the development of novel biologics—synthetic mRNAs and Sendai virus vectors encoding human ZSCAN4—which can efficiently increase cells with normal karyotypes in mouse ES cells as well as in non-immortalized primary human fibroblast cells derived from people with DS or Edwards syndrome (Trisomy 18).19 These results motivate further work to test possible applications of ZSCAN4 biologics to treat chromosome abnormalities. Here, ZSCAN4 is linked to trisomy 18.