SMC1A and Cornelia de Lange syndrome: For example, most patients with variants in SMC1A show milder developmental delay and intellectual disability compared to their classical NIPBL-CdLS counterparts, but about 40% of SMC1A patients exhibit severe epileptic encephalopathy and intellectual disability (Jansen et al. 2016; Symonds et al. 2017; Selicorni et al. 2021).CdLS has also been reclassified as a spectrum of cohesinopathies (Van Allen et al. 1993; Kline et al. 2018).