LRPAP1 and Intellectual disability: SYNGAP1 is a pathogenic gene for intellectual disability including mental retardation, epilepsy, and autism spectrum disorders (Mignot et al., 2016), and SYNGAP1 is a major protein located at the postsynaptic density and negatively regulates the Ras/Rap pathway (Kim et al., 1998; Jeyabalan and Clement, 2016; Walkup et al., 2016).