SYNGAP1 and epilepsy: Large genetic studies of ASD, epilepsy and ID cohorts have also identified de novo variants in RAS-related genes, among which SYNGAP1 appears among the most significant [19,28,60] Among 5649 de novo mutations in a large exome sequencing study by Iossifov and colleagues [20] the mutations in SYNGAP1 were the highest at five, followed by LZTR1 at four and NF1 at three individuals identified.