Since its discovery, genetic variations in the GRIN2B translating into GluN2B protein have consistently been linked to West syndrome, intellectual impairment with focal epilepsy, developmental delay, macrocephaly, corticogenesis, brain plasticity, as well as infantile spasms and Lennox–Gastaut syndrome [5,60,61,62,63]. Here, GRIN2B is linked to Global developmental delay.