NIPBL and Cornelia de Lange syndrome: To date, five genes (i.e., NIPBL, SMC1A, SMC3, RAD21, and HDAC8) have been associated with the CDLS classic phenotype (Krantz et al., 2004; Tonkin et al., 2004; Musio et al., 2006; Deardorff et al., 2007; Deardorff et al., 2012; Deardorff et al., 2012; Yuan et al., 2019), and NIPBL is considered the major gene as it accounts for 70%–80% of the loss-of-function defects in the patients (Kaiser et al., 2014; Boyle et al., 2015).