The emerging picture is that the ARID1B-associated phenotype is highly variable with mild to severe ID, severe expressive speech impairment or absent speech (even in patients who may be capable of other forms of communication), corpus callosum anomalies in up to 1/3 of patients, autism in a significant fraction of patients, and a coarse facial appearance reminiscent of CSS in most patients. This evidence concerns the gene ARID1B and autism.