RAD21 and Cornelia de Lange syndrome: A total of seven genes have been identified in association with CdLS, including NIPBL (~50–70%), SMC1A, SMC3, BRD4, HDAC8 (~4%), RAD21, and ANKRD11. Roberts syndrome is an autosomal recessive disorder related phenotypically to CdLS, with affected patients demonstrating facial dysmorphisms, limb reduction and growth retardation.