SYNGAP1 and Intellectual disability: Interestingly, reduced levels of SynGAP1, a synaptic Ras/Rap GTPase activating protein (Chen et al., 1998; Kim et al., 1998) in humans, can cause a syndromic form of intellectual disability (Holder et al., 1993; Chen et al., 1998; Kim et al., 1998) and also produce enhanced mGluR-dependent, protein synthesis independent LTD in mouse hippocampus (Barnes et al., 2015).