GRIN2B and attention deficit-hyperactivity disorder: GRIN1 and GRIN2B polymorphisms, in particular, have been found to be associated with infantile spasms [47], neurodevelopmental disorders [48], Alzheimer’s Disease [49], Parkinson’s Disease [50], schizophrenia [51], obsessive-compulsive disorder [52], attention/deficit hyperactivity disorder [53], and bipolar disorder [54], confirming a widespread and essential role of NMDARs in brain function and dysfunction.