Individuals with SYNGAP1-ID often have severe to profound intellectual disability, gross motor delays, and features of autism spectrum disorder (ASD) (Squire et al., 1990; Hamdan et al., 2011; Holder et al., 2019; Jimenez-Gomez et al., 2019; Vlaskamp et al., 2019) that are most frequently due to de novo autosomal dominant loss-of-function or missense mutations in the SYNGAP1 gene. The gene discussed is SYNGAP1; the disease is autism spectrum disorder.