GRIN2B variations have been identified in GRIN2B-related neurodevelopmental disorders, such as ID [5], ASD [6,7], Atypical Rett Syndrome & intractable epilepsy [8], encephalopathy [9], developmental delay or macrocephaly [10], schizophrenia [11], obsessive compulsive disorder [12], and cerebral visual impairment [13], causing cells to create an inactive GluN2B protein or prevent them from making any GluN2B protein. Here, GRIN2B is linked to atypical Rett syndrome.