In a previous study of a CdLS mouse model of Nipbl haploinsufficiency (Nipbl+/- mice), we reported that about half of Nipbl+/- mice display defects in closure of the atrial septum (ASD) between gestational days 15.5 and 17.5 (E15.5–E17.5) [22]. Here, NIPBL is linked to Cornelia de Lange syndrome.