Relatively minor changes in early mesoderm cell population numbers have recently been reported to associate with later heart defects in a mouse model of Cornelia de Lange syndrome using NPBL1+/- mice (Chea et al., 2024), and thus GATA6 heterozygous mutations may similarly have a subtle negative effect on developing mesodermal cell populations to cause CHD. Here, GATA6 is linked to Cornelia de Lange syndrome.