RAD21 and Cornelia de Lange syndrome: Cornelia de Lange syndrome (CdLS) is a member of a class of developmental disorders referred to as cohesinopathies, which result from mutations in any of seven genes encoding subunits or regulators of the cohesin complex (NIPBL, SMC1A, SMC3, RAD21, HDAC8 SMC1A, SMC3, RAD21, BRD4, HDAC8 and ANKRD11) [4].