Mutations in genes encoding components of the BAF complex, such as ARID1B, ARID1A, ARID2, SMARCA2, SMARCA4, SMARCB1, SMARCC2, SMARCE1, SOX11, DPF2, and BICRA, cause a range of disorders, including syndromic intellectual disability, Coffin-Siris syndrome (CSS), and Nicolaides-Baraitser syndrome (NCBRS) (6, 12–18). This evidence concerns the gene ARID1B and syndromic intellectual disability.