Given that SYNGAP1 is a well-established NDD gene and LOF mutations are highly penetrant in the human population (Deciphering Developmental Disorders Study, 2015; Deciphering Developmental Disorders Study, 2017; Hamdan et al., 2009; Parker et al., 2015; Mignot et al., 2016; Satterstrom et al., 2020; Hamdan et al., 2011; Berryer et al., 2013), studying these relationships have the potential to provide much needed insight into the neurobiology underlying human cognitive and behavioral disorders that first manifest during development. The gene discussed is SYNGAP1; the disease is Neurodevelopmental delay.