SOX11 is itself induced by the BAF (BRG1-associated or HRBM-associated factors) complex, leading to neuronal differentiation.32 It is noteworthy that many other genes mutated in CSS function in the BAF complex.32 The majority of genes in the BAF complex in which mutations have been identified are associated with a CSS phenotype (eg, ARID1A, ARID1B, SMARCB1, SMARCA4 and SMARCE1), while mutations in SMARCA2 cause Nicolaides–Baraitser syndrome.31 Our report thus reinforces the importance of the BAF complex in CSS. Here, ARID1B is linked to Coffin-Siris syndrome.