Exome sequencing further established STAG1 and STAG2 variants in individuals with cohesinopathy phenotypes as loss of function (Yuan et al., 2019), and, recently, loss-of-function variants of STAG2 have been categorized as X-linked cohesinopathies with features of CdLS (Mullegama et al., 2017; Soardi et al., 2017). The gene discussed is STAG2; the disease is Cornelia de Lange syndrome.