Some patient-derived cell lines with mutations in the cohesin loader NIPBL revealed loss of sister chromatid cohesion phenotypes, but evaluations of patient-derived cell lines with SMC1A mutations and lymphocytes from CdLS patients reported no obvious sister cohesion defects (Castronovo et al. 2009; Revenkova et al. 2009). Here, SMC1A is linked to Cornelia de Lange syndrome.