Deleterious mutations in the gene SCN2A, which encodes the voltage-gated sodium channel Nav1.2, constitute one of the leading risk factors for neurodevelopmental disorders, increasing the odds of developing autism spectrum disorder and intellectual disability (ASD/ID) to levels beyond those calculable from studies of large cohorts (e.g., an infinite odds-ratio; Sanders et al., 2012; Ben-Shalom et al., 2017; Satterstrom et al., 2020; Fu et al., 2022; Rolland et al., 2023). The gene discussed is SCN2A; the disease is Intellectual disability.