The chromosomal localization of SUPYN overlaps with the Down syndrome critical region, so we could hypothesize that an increased copy number of the SUPYN locus in trisomy 21 affected placentas could be important in the context of abnormal placenta morphology in Down syndrome, which is characterized by delayed maturation of cytotrophoblast cells and reduced syncytialization [102]. Here, ERVH48-1 is linked to Down syndrome.