CdLS affects approximately 1 in 10 000 to 30 000 newborns (Kline et al. 2007; Kline et al. 2018; Mannini et al. 2013) and results from mutations in the NIPBL (Krantz et al. 2004), SMC1A, HDAC8, RAD21 (Deardorff et al. 2012; Deardorff et al. 2016), BRD4, ANKRD11 (Kline et al. 2018) and SMC3 (Revenkova et al. 2009) genes as well as mosaicism for NIPBL mutations (Ansari et al. 2014; Huisman et al. 2013), which disrupt gene regulation during early critical development. The gene discussed is NIPBL; the disease is Cornelia de Lange syndrome.