GRIN2A and Intellectual disability: There is evidence that GRIN2A and GRIN2B variants are associated with typical phenotypic characteristics: intellectual disability is associated with variants in genes encoding either the GluN2A or the GluN2B subunit, epilepsy is typical for variants in the gene for GluN2A, and autism spectrum disorder is typical for variants in the gene encoding GluN2B [2, 12, 76–78].