In addition to ASD and ID, patients with ASH1L mutations also display a variety of developmental and behavioral abnormalities, including delayed myelination, microcephaly, craniofacial deformity, skeletal abnormality, and feeding difficulties, suggesting critical roles of ASH1L in normal embryonic and postnatal development (Shen et al., 2019; Okamoto et al., 2017; de Ligt et al., 2012). The gene discussed is ASH1L; the disease is microcephaly.