SYNGAP1 and Cognitive impairment: However, considering the remarkable findings of Smalheiser et al. (2011), who identified an endogenous siRNA complementary to SynGAP1, and that dysregulation of SynGAP1 correlates with mental retardation as well as autism (Hamdan et al., 2009), these observations suggest a potentially important role for endogenous siRNA in cognitive disorders.