Lemke JR, etal., Ann Neurol. 2014 Jan;75(1):147-54. doi: 10.1002/ana.24073. Epub 2014 Jan 2.
OBJECTIVE: To identify novel epilepsy genes using a panel approach and describe the functional consequences of mutations. METHODS: Using a panel approach, we screened 357 patients comprising a vast spectrum of epileptic disorders for defects in genes known to contribute to epile
psy and/or intellectual disability (ID). After detection of mutations in a novel epilepsy gene, we investigated functional effects in Xenopus laevis oocytes and screened a follow-up cohort. RESULTS: We revealed de novo mutations in GRIN2B encoding the NR2B subunit of the N-methyl-D-aspartate (NMDA) receptor in 2 individuals with West syndrome and severe developmental delay as well as 1 individual with ID and focal epilepsy. The patient with ID and focal epilepsy had a missense mutation in the extracellular glutamate-binding domain (p.Arg540His), whereas both West syndrome patients carried missense mutations within the NR2B ion channel-forming re-entrant loop (p.Asn615Ile, p.Val618Gly). Subsequent screening of 47 patients with unexplained infantile spasms did not reveal additional de novo mutations, but detected a carrier of a novel inherited GRIN2B splice site variant in close proximity (c.2011-5_2011-4delTC). Mutations p.Asn615Ile and p.Val618Gly cause a significantly reduced Mg(2+) block and higher Ca(2+) permeability, leading to a dramatically increased Ca(2+) influx, whereas p.Arg540His caused less severe disturbance of channel function, corresponding to the milder patient phenotype. INTERPRETATION: We identified GRIN2B gain-of-function mutations as a cause of West syndrome with severe developmental delay as well as of ID with childhood onset focal epilepsy. Severely disturbed channel function corresponded to severe clinical phenotypes, underlining the important role of facilitated NMDA receptor signaling in epileptogenesis.
Hassan A, etal., Parkinsonism Relat Disord. 2016 Jan;22:102-5. doi: 10.1016/j.parkreldis.2015.11.016. Epub 2015 Nov 25.
INTRODUCTION: Dopamine and glutamate are crucial neurotransmitters in Parkinson disease (PD). While recent large meta-analyses reported that genetic variation of dopamine (DRD2, DRD3) and glutamine (NMDA, GRIN2B) neurotransmitter receptors was not associated wit
h PD risk, they could conceivably influence PD phenotype. We studied the association of these receptor polymorphisms relating to PD age of onset. METHODS: There were 664 PD patients and 718 controls, all Caucasian, with stored DNA at Mayo Clinic, Jacksonville, Florida. Genotyping was performed for DRD2 (Taq 1A, rs1800497), DRD3 (rs6280), and NMDA (GRIN2B, rs7301328) polymorphisms with ABI Taqman assays. Single nucleotide polymorphism associations with age of onset were evaluated using dominant, recessive, and additive genotypic models. RESULTS: DRD3 variant carriers had an approximate 4.4-year decrease in mean age of onset when both copies of the minor allele were present (P = 0.0034) and an approximate 1.5-year decrease in mean age at onset for every additional minor allele (P = 0.023) (recessive and additive models, respectively). There was no association with age of onset for DRD2 or GRIN2B under any statistical model (all P >/= 0.22). CONCLUSIONS: The DRD3 (rs6280) polymorphism, but not DRD2 (Taq1A) or GRIN2B, influences younger PD age of onset in the US Caucasian population. Validation of these findings in larger studies with other ethnic groups is indicated.
Che F, etal., J Affect Disord. 2015 Nov 15;187:62-5. doi: 10.1016/j.jad.2015.07.036. Epub 2015 Aug 21.
BACKGROUND: Previous studies have indicated that dopamine interacts with glutamatergic projection neurons and that N-methyl-d-aspartate (NMDA) receptors might be involved in the pathogenesis of Tourette syndrome (TS). In this study, we examined whether two functional polymorphisms (rs1805476 and rs1
805502) in the 3'UTR of the NMDA receptor 2B subunit gene (GRIN2B) were associated with TS in Chinese Han trios. METHODS: DNA samples collected from 261 TS nuclear families were genotyped by PCR and direct sequencing technology. Haplotype relative risk (HRR), transmission disequilibrium test (TDT) and Haplotype-based haplotype relative risk (HHRR) analyses were performed on the genotype data. RESULTS: We found an over-transmission of the A allele in rs1805476 and the T allele in rs1805502 from parents to their affected children, using the HRR (rs1805476: HRR=0.696, chi(2)=4.161, P=0.041, 95% CI: 0.491-0.986; rs1805502: HRR=0.697, chi(2)=3.954, P=0.047, 95% CI: 0.488-0.995). There was also strong evidence for a linkage between polymorphisms and TS using the TDT (rs1805476: TDT=5.447, df=1, P=0.024; rs1805502: TDT=5.233, df=1, P=0.027). LIMITATIONS: The sample is small and the current population is just limited to the Chinese Han population. CONCLUSIONS: These data support the hypothesis that GRIN2B might play a major role in the pathogenesis of TS in Chinese Han trios. However, these results need to be replicated using larger datasets collected from different populations.
Hristova K, etal., Epilepsia. 2025 Aug 19. doi: 10.1111/epi.18606.
OBJECTIVE: Pathogenic mutations in GRIN2B are an important cause of severe neurodevelopmental disorders resulting in epilepsy, autism, and intellectual disability. GRIN2B encodes the GluN2B subunit of N-methyl-d-a
spartate receptors (NMDARs), which are ionotropic glutamate receptors critical for normal development of the nervous system and synaptic plasticity. Here, we characterized a novel Grin2b heterozygous knockout rat model with electroencephalography (EEG) and pharmacological interventions to block spontaneous seizures. METHODS: Through western blot analysis we assessed the extent of GluN2B protein knockdown in knockout (Grin2b+/-) rats compared to controls. We recorded 24-h wireless multi-channel EEG to test whether seizure activity was present and analyzed sleep-wake cycles through a novel automated sleep-scoring algorithm. We tested the effects of systemic and intracerebral reticular thalamic nucleus administration of ethosuximide, a T-type voltage-gated calcium channel blocker, and memantine, a noncompetitive NMDAR antagonist, on seizures. RESULTS: Compared to wild-type rats, Grin2b+/- rats had a higher incidence of spontaneous spike and wave discharges (SWDs), the electrographic correlate of absence seizures. SWDs were longer in duration and displayed higher delta band spectral power in Grin2b+/- animals. Heterozygous animals displayed a reduction in total rapid eye movement sleep and altered distributions of non-rapid eye movement sleep and wake epochs. This was accompanied by a decrease in overall spectral wake power and an increase in beta band power during non-rapid eye movement sleep. The sleep-wake phenotypes were largely uncorrelated with the incidence of SWDs. Systemic ethosuximide reduced the number and duration of SWDs, whereas memantine only reduced their duration. Intrathalamic infusion of both ethosuximide and memantine reduced the number of SWDs. SIGNIFICANCE: Our data show that the new rat Grin2b haploinsufficiency model exhibits clinically relevant phenotypes and highlights two potential therapeutic options for GRIN2B-related epilepsy.
Chronic obstructive pulmonary disease (COPD) is a complex chronic inflammatory disease of the respiratory system that affects primarily distal respiratory pathways and lung parenchyma. Smoking tobacco is a major risk factor for COPD. The relationship of HTR4 (rs3995090), HTR2A (rs6313), GRIK5 (rs809
9939), GRIN2B (rs2268132), and CHRNB4 (rs1948) gene polymorphisms and COPD, as well as the contribution of these polymorphisms to the variations in quantitative characteristics that describe respiratory function, smoking behavior, and nicotine dependence was assessed in an ethnically homogeneous Tatar population. The polymorphisms of HTR2A (rs6313) (P = 0.026, OR = 1.42 for the CC genotype) and GRIN2B (rs2268132) (P = 0.0001, OR = 2.39 for the TT genotype) were significantly associated with increased risk of COPD. The AA genotype of GRIK5 (rs8099939) had a protective effect (P = 0.02, OR = 0.61). Importantly, the HTR2A (rs6313), GRIN2B (rs2268132), and GRIK5 (rs8099939) polymorphisms were only associated with COPD in smokers. Smoking index (pack-years) was significantly higher in carriers of the GRIK5 genotype AC (rs8099939) (P = 0.0027). The TT genotype of GRIN2B (rs2268132) was associated with COPD in subjects with high nicotine dependence according to the Fagerstrõm test (P = 0.002, OR = 2.98). The TT genotype of HTR2A (rs6313) was associated with a reduced risk of the disease in the group with moderate nicotine dependence (P = 0.02, OR = 0.22). The CC genotype of HTR2A (rs6313) and the TT genotype of GRIN2B (rs2268132) were associated with higher levels of nicotine dependence according to the Fagerstrõm test (P = 0.0011 and P = 0.037). Our results may provide insight into potential molecular mechanisms that involve the glutamate (GRIK5, GRIN2B) and serotonin (HTR2A) receptor genes in the pathogenesis of COPD.
BACKGROUND: The glutamatergic neurotransmitter systems play a crucial role in memory formation and information processing. Alterations in this system contribute to the manifestation of symptoms in Alzheimer's disease (AD). Glutamate transmits signals via the N-methyl-D-aspartate receptors
(NMDARs). AIMS: The potential involvement of polymorphisms in the GRIN2B gene, encoding subunit 2B of the NMDA receptor, in the risk for AD was evaluated. METHODS: We investigated the 3 single-nucleotide polymorphisms (SNPs) rs1019385, rs1806201 and rs890, i.e. the G(-200)-->T transversion in the 5'UTR, the A(2664)-->G transition in exon 13 and the G(5072)-->T transition in the 3'UTR of the GRIN2B gene, in 222 Caucasian AD patients and 170 healthy Caucasian age-matched controls. RESULTS: No differences were found in the overall distribution of the single-nucleotide polymorphism genotypes between AD patients and healthy controls, even when the analysis was adjusted for sex, age and APOE. As expected from genotype frequencies, no differences were found in the distribution of the estimated allele and haplotype frequencies between AD patients and healthy controls. CONCLUSION: In this study no significant association between polymorphisms in the GRIN2B gene and AD was observed. Further investigations of polymorphisms in the gene encoding the NMDA receptor 2B subunit in AD patients with different genetic setting are needed to clarify their role in the pathogenesis of AD.
Jiang H and Jia J, Neurosci Lett. 2009 Feb 6;450(3):356-60. doi: 10.1016/j.neulet.2008.10.075. Epub 2008 Oct 25.
N-methyl-d-aspartate (NMDA) receptor plays a crucial role in learning, memory and information processing of human brain. Its dysfunction is related to the pathogenesis of Alzheimer's disease (AD). We detected four polymorphisms of the promoter regions of the human NMDA receptor 2B (NR2B) subunit gen
e (GRIN2B) in 362 AD patients and 334 healthy in North Han Chinese populations, these were -200T/G (rs1019385), -421C/A (rs3764028), -1447T/C (ENS10557853), and -1497G/A (rs12368476). Genetic analysis confirmed that there were significant differences in genotype (P=0.029) and allele (P=0.010) frequencies for -421C/A between SAD and control. In the subjects without APOE varepsilon4 allele, these difference remained significant (genotype P=0.012, allele P=0.004). The -421CC genotype was about 1.5 fold increasing risk compared with CA+AA genotypes (OR=1.517, 95% CI 1.077-2.137, P=0.017). Luciferase reporter assay showed a 34.69-39.79% decrease in transcriptional activity for -421C allele of GRIN2B promoter compared with -421A in SH-SY5Y and HeLa cell lines. Our study suggests that the -421C allele may induce lower GRIN2B transcriptional activity and NR2B protein expression, thus it is associated with AD.
Schizophrenia is a severe mental illness to which hypofunction of the N-methyl-D-aspartate receptors has been linked. Association studies have implicated the N-methyl-D-aspartate receptor 2B subunit gene (GRIN2B) as a candidate for schizophrenia. Subsequent stud
ies have attempted to replicate the association, but the results have been mixed and thus inconclusive. It is necessary to explain the inconsistency of these results and to clarify the contribution of the GRIN2B gene to schizophrenia. The current meta-analysis covers all published association studies up to January 2006 using systematic allelic and genotypic analyses involving five polymorphisms. The results show evidence of a statistically significant association for GRIN2B. The association seems weaker, but nonetheless interesting. The meta-analysis supports the involvement of the glutamate system of the brain in the pathogenesis of schizophrenia. This may be the first systematic meta-analysis study focusing on GRIN2B.
Yang Y, etal., PLoS One. 2015 May 28;10(5):e0125925. doi: 10.1371/journal.pone.0125925. eCollection 2015.
Schizophrenia (SZ) is a common and complex psychiatric disorder that has a significant genetic component. The glutamatergic system is the major excitatory neurotransmitter system in the central nervous system, and is mediated by N-methyl-D-aspartate (NMDA) receptors. Disturbances in this system have
been hypothesized to play a major role in SZ pathogenesis. Several studies have revealed that the NMDA receptor subunit 2B (GRIN2B) potentially associates with SZ and its psychiatric symptoms. In this study, we performed a case-control study to identify polymorphisms of the GRIN2B gene that may confer susceptibility to SZ in the Han Chinese population. Thirty-four single nucleotide polymorphisms (SNPs) were genotyped in 528 paranoid SZ patients and 528 control subjects. A significant association was observed in allele and genotype between SZ and controls at rs2098469 (chi2 = 8.425 and 4.994; p = 0.025 and 0.014, respectively). Significant associations were found in the allele at rs12319804 (chi2 = 4.436; p = 0.035), as well as in the genotype at rs12820037 and rs7298664 between SZ and controls (chi2 = 11.162 and 38.204; p = 0.003 and 4.27x10(-8), respectively). After applying the Bonferroni correction, rs7298664 still had significant genotype associations with SZ (p = 1.71x10(-7)). In addition, rs2098469 genotype and allele frequencies, and 12820037 allele frequencies were nominally associated with SZ. Three haplotypes, CGA (rs10845849-rs12319804-rs10845851), CC (rs12582848-rs7952915), and AAGAC (rs2041986-rs11055665-rs7314376-rs7297101-rs2098469), had significant differences between SZ and controls (chi2 = 4.324, 4.582, and 4.492; p = 0.037, 0.032, and 0.034, respectively). In addition, three SNPs, rs2098469, rs12820037, and rs7298664, were significantly associated with cognition factors PANSS subscores in SZ (F = 16.799, 7.112, and 13.357; p = 0.000, 0.017, and 0.000, respectively). In conclusion, our study provides novel evidence for an association between GRIN2B polymorphisms and SZ susceptibility and symptoms in the Han Chinese population.
The N-methyl-D-aspartate (NMDA) receptor 2B gene (GRIN2B) was studied as a candidate gene of alcoholism. This study aimed to investigate the association between each of the three GRIN2B polymorphisms (rs1806201, rs1805247, a
nd rs1805502) and alcoholism. This study included 206 alcoholic patients and 189 unrelated control subjects of Korean origin. Associations between genotype, allele, and haplotype frequencies of the polymorphisms and alcoholism were investigated. The genotype frequencies of rs1806201 and the haplotype analysis of SNPs in this study show significantly differences between the case and controls. These findings suggest new candidate SNPs in GRIN2B for studying the genetic susceptibility to alcoholism.
BACKGROUND: Impulse control disorder (ICD) and behaviours (ICB) represent a group of behavioural disorders that have become increasingly recognised in Parkinson's disease (PD) patients who previously used dopaminergic medications, particularly dopamine agonists and levodopa. It has been suggested
that these medications can lead to the development of ICB through the abnormal modulation of dopaminergic transmission and signalling in the mesocorticolimbic dopaminergic system. Several studies have reported an association between polymorphisms in the dopamine receptor (DRD) and N-methyl-D-aspartate 2B (GRIN2B) genes with the development of ICB in PD (PD-ICB) patients. Thus, this study aimed to investigate the association of selected polymorphisms within the DRD and GRIN2B genes with the development of ICB among PD patients using high resolution melt (HRM) analysis. METHOD: We used high resolution melt (HRM) analysis to genotype 11 polymorphisms in 5 DRD genes [DRD1 (rs4532, rs4867798 and rs265981), DRD2 (ANKK1 rs1800497, rs104894220 and rs144999500), DRD3 (rs3732783 and rs6280), DRD4 (rs1800443), and DRD5 (rs144132215)] and 1 polymorphism in GRIN2B (rs7301328) in PD patients with (cases, n = 52) and without (controls, n = 39) ICB. Cases were obtained from two tertiary movement disorder centres [UKMMC (n = 9) and UMMC (n = 43)]. At both centres, the diagnosis of ICB was made using the QUIP questionnaire. Controls were recruited from PD patients who attended UKMMC and were found to be negative for ICB using the QUIP questionnaire. RESULTS: The HRM analysis showed that 7 of 11 polymorphisms [DRD1 (rs4532, rs4867798, and rs265981), DRD2 (ANKK1 rs1800497), DRD3 (rs3732783 and rs6280), and GRIN2B (rs7301328)] exhibited a clear distinction between wild-type and variant alleles. Variants of DRD2/ANKK1 rs1800497 (OR = 3.77; 95% CI, 1.38-10.30; p = 0.0044), DRD1 rs4867798 (OR = 24.53; 95% CI, 1.68-357.28; p = 0.0054), DRD1 rs4532 (OR = 21.33; 95% CI, 1.97-230.64; p = 0.0024), and GRIN2B rs7301328 (OR = 25.07; 95% CI, 1.30-483.41; p = 0.0097) were found to be associated with an increased risk of developing ICB among PD patients. CONCLUSION: Our findings suggest that polymorphisms in dopamine [DRD1 (rs4532 and rs4867798) and DRD2/ANKK1 rs1800497] and glutamate (GRIN2B rs7301328) receptor genes confer increased risk of ICB development among PD patients.
Taylor DL, etal., Hum Psychopharmacol. 2016 Mar;31(2):121-34. doi: 10.1002/hup.2519. Epub 2016 Feb 15.
OBJECTIVE: Approximately 30% of patients with schizophrenia fail to respond to antipsychotic therapy and are classified as having treatment-resistant schizophrenia. Clozapine is the most efficacious drug for treatment-resistant schizophrenia and may deliver superior therapeutic effects pa
rtly by modulating glutamate neurotransmission. Response to clozapine is highly variable and may depend on genetic factors as indicated by twin studies. We investigated eight polymorphisms in the N-methyl-D-aspartate glutamate receptor subunit gene GRIN2B with response to clozapine. METHODS: GRIN2B variants were genotyped using standard TaqMan procedures in 175 European patients with schizophrenia deemed resistant or intolerant to treatment. Response was assessed using change in Brief Psychiatric Rating Scale scores following six months of clozapine therapy. Categorical and continuous response was assessed using chi-squared test and analysis of covariance, respectively. RESULTS: No associations were observed between the variants and response to clozapine. A-allele carriers of rs1072388 responded marginally better to clozapine therapy than GG-homozygotes; however, the difference was not statistically significant (p = 0.067, uncorrected). CONCLUSIONS: Our findings do not support a role for these GRIN2B variants in altering response to clozapine in our sample. Investigation of additional glutamate variants in clozapine response is warranted.
N-methyl-D-aspartate (NMDA) receptors mediate excitatory neurotransmission in the mammalian brain. Two glycine-binding NR1 subunits and two glutamate-binding NR2 subunits each form highly Ca(2)(+)-permeable cation channels which are blocked by extracellular Mg(2)(+) in a voltage-dependent manner. Ei
ther GRIN2B or GRIN2A, encoding the NMDA receptor subunits NR2B and NR2A, was found to be disrupted by chromosome translocation breakpoints in individuals with mental retardation and/or epilepsy. Sequencing of GRIN2B in 468 individuals with mental retardation revealed four de novo mutations: a frameshift, a missense and two splice-site mutations. In another cohort of 127 individuals with idiopathic epilepsy and/or mental retardation, we discovered a GRIN2A nonsense mutation in a three-generation family. In a girl with early-onset epileptic encephalopathy, we identified the de novo GRIN2A mutation c.1845C>A predicting the amino acid substitution p.N615K. Analysis of NR1-NR2A(N615K) (NR2A subunit with the p.N615K alteration) receptor currents revealed a loss of the Mg(2)(+) block and a decrease in Ca(2)(+) permeability. Our findings suggest that disturbances in the neuronal electrophysiological balance during development result in variable neurological phenotypes depending on which NR2 subunit of NMDA receptors is affected.
The NR2B protein is a critical structural and functional subunit of the NMDA glutamate receptor. The glutamate neurotransmitter system has been implicated in psychosis and schizophrenia, and so we looked for genetic association and measured gene expression in human DNA and brain samples, respectivel
y, of the GRIN2B gene that codes for the NR2B protein. We tested three genetic polymorphisms: G-200T (5'UTR), A5806C and T5988C (both 3'UTR) in 180 matched schizophrenia case-control pairs, 86 schizophrenia nuclear family trios, and 318 bipolar disorder trios (of which 158 probands had psychotic symptoms). We measured brain GRIN2B mRNA levels in schizophrenia, bipolar disorder and unaffected controls (n = 35 each). We detected genetic association between the G-200T marker and schizophrenia (p = 0.002), between T5988C and bipolar disorder (p = 0.02), and between A5806C and bipolar disorder with psychotic symptoms (p = 0.0038). The T-C-C haplotype was transmitted more frequently with bipolar disorder, but less often with schizophrenia, while the G-C-T haplotype was transmitted more often in schizophrenia. Significant differences were found in overall haplotype frequencies between schizophrenia cases and controls (p = 0.005). GRIN2B expression levels in schizophrenia, bipolar disorder and controls were not significantly different. The genetic findings suggest a role for GRIN2B in schizophrenia and bipolar disorder.
Increasing evidence links dysregulation of NR2B-containing N-methyl-D-aspartate receptor remodelling and trafficking to Alzheimer's disease (AD). This theme offers the possibility that the GRIN2B gene, encoding this selective NR2B subunit, represents a potential
molecular modulating factor for this disease. Based on this hypothesis, we carried out a mutation scanning of exons and flanking regions of GRIN2B in a well-characterized cohort of AD patients, recruited from Southern Italy. A "de novo" p.K1293R mutation, affecting a highly conserved residue of the protein in the C-terminal domain, was observed for the first time in a woman with familial AD, as the only genetic alteration of relevance. Moreover, an association study between the other detected sequence variants and AD was performed. In particular, the study was focused on five identified single nucleotide polymorphisms: rs7301328, rs1805482, rs3026160, rs1806191 and rs1806201, highlighting a significant contribution from the GRIN2B rs1806201 T allele towards disease susceptibility [adjusted odds ratio (OR) = 1.92, 95% confidence interval (CI) 1.40-2.63, p < 0.001, after correction for sex, age, and APOE e4 genotype]. This was confirmed by haplotype analysis that identified a specific haplotype, carrying the rs1806201 T allele (CCCTC), over-represented in patients versus controls (adjusted OR = 6.03; p < 0.0001). Although the pathogenic role of the GRIN2B-K1293R mutation in AD is not clear, our data advocate that genetic variability in the GRIN2B gene, involved in synaptic functioning, might provide valuable insights into disease pathogenesis, continuing to attract significant attention in biomedical research on its genetic and functional role.
