ARID1A (the AT‐rich interaction domain 1A, also known as BAF250a), the largest subunit of the SWI/SNF chromatin remodeling complex, has been reported that its mutations are closely related to Coffin–Siris syndrome (CSS), which is characterized by intellectual disability, growth deficiency and microcephaly.14, 15, 16. Here, ARID1A is linked to microcephaly.