RAD21 and Cornelia de Lange syndrome: Heterozygous mutations in five genes (NIPBL, SMC1A, SMC3, HDAC8, and RAD21) have been found to be contributory to CdLS, with NIPBL gene (NM_133433.3, NG_006987.2 RefSeqGene) mutations responsible for approximately 50% of CdLS cases (Mannini, Cucco, Quarantotti, Krantz, & Musio, 2013).