Importantly, the realization that mutants in the cohesin loading subunit NIPBL cause Cornelia de Lange Syndrome (CdLS), a developmental disorder resulting in severe malformations and mental retardation [297], [298], [299], led to the discovery of a class of human genetic diseases known as cohesinopathies [300], [301], [302]. The gene discussed is NIPBL; the disease is Cornelia de Lange syndrome.