GRIN2B (Glutamate NMDA receptor subunit epsilon-2, NMDAR2B) is an ionotropic glutamate receptor and a primary excitatory neurotransmitter receptor that functions in long-term potentiation (LTP). The ratio of GRIN2B to GRIN2A expression modulates the strength of excitatory LTP in neurons, and mice with increased native GRIN2B expression have demonstrated increased mental ability. Mutations in GRIN2B disrupt proper neuronal differentiation and lead to GRIN2B-related neurodevelopmental disorder, characterized by developmental delay, cognitive impairment, visual impairment and microcephaly. In immunohistochemistry, GRIN2B is specific to the brain and has cytoplasmic positivity in Purkinje cells. References: PLOS ONE. 4 (10): e7486. doi:10.1371/journal.pone.0007486. PMC 2759522. PMID 19838302; GeneReviews. University of Washington. 2018 May. PMID: 29851452; Stem Cell Reports. 2018 Jul 10;11(1):183-196, PMID: 29937144;