This Editorial highlights an article by Gulchina and colleagues in the current issue of the Journal of Neurochemistry, in which the authors describe molecular and epigenetic changes in the developing prefrontal cortex of the rats exposed to methylazoxymethanol acetate (MAM). They found an NMDAR hypofunction present in the prefrontal cortex of juvenile MAM rats which was associated with abnormal epigenetic regulation of the Grin2b gene. These changes may be related to early cognitive impairments observed in MAM rats and schizophrenia patients.

Glutamatergic neurotransmission has been shown to be dysregulated in bipolar disorder (BD), alcohol use disorder (AUD) and substance use disorder (SUD). Similarly, disruption in the hypothalamic-pituitary-adrenal (HPA)-axis has also been observed in these conditions. BD is often comorbid with AUD and SUD. The effects of the glutamatergic and HPA systems have not been extensively examined in individuals with BD-AUD and BD-SUD comorbidity. The aim of this investigation was to determine whether variants in the glutamatergic pathway and HPA-axis are associated with BD-AUD and BD-SUD comorbidity. The research cohort consisted of 498 individuals with BD type I from the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD). A subset of the cohort had comorbid current AUD and current SUD. A total of 1935 SNPs from both the glutamatergic and HPA pathways were selected from the STEP-BD genome-wide dataset. To identify population stratification, IBS clustering was performed using the program Plink 1.07. Single SNP association and gene-based association testing were conducted using logistic regression. A pathway analysis of glutamatergic and HPA genes was performed, after imputation using IMPUTE2. No single SNP was associated with BD-AUD or BD-SUD comorbidity after correction for multiple testing. However, from the gene-based analysis, the gene PRKCI was significantly associated with BD-AUD. The pathway analysis provided overall negative findings, although several genes including GRIN2B showed high percentage of associated SNPs for BD-AUD. Even though the glutamatergic and HPA pathways may not be involved in BD-AUD and BD-SUD comorbidity, PRKCI deserves further investigation in BD-AUD.

Previous investigations have provided evidence that some polymorphisms in the 3' untranslated region (3'-UTR) of GRIN2B are associated with susceptibility to obsessive-compulsive disorder (OCD). We evaluated the genetic contribution of the rs1805502, rs1805476 and rs890 polymorphisms in the 3'-UTR of GRIN2B in 206 OCD patients and 413 controls in a Chinese Han population, and found no significant differences in genotypic and allelic frequencies between OCD cases and the controls. Our results suggest the lack of an association between OCD and polymorphisms in the 3'-UTR of GRIN2B in a Chinese Han population.

In the mouse cerebellum, Ca2+-dependent activator protein for secretion 2 (CADPS2, CAPS2) is involved in regulated secretion from dense-core vesicles (DCVs), which contain neuropeptides including brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3). Capds2 knockout (KO) mice show impaired cerebellar development in addition to autistic-like behavioral phenotypes. To understand the molecular impact caused by loss of Capds2, we analyzed gene expression profiles in the Capds2 KO cerebellum using a GeneChip microarray and the KEGG Pathway database. Significant differential expression was observed in 1211 of 22,690 (5.34%) genes represented on the chip. The expression levels of exocytosis-related genes (Stx5a, Syt6), genes encoding secretory (Fgf2, Fgf4, Edn2) and synaptic proteins (Grin2b, Gabbr1), neurotrophin signaling-associated genes (Sos1, Shc1, Traf6, Psen2), and a gene for Rett syndrome (Mecp2) were significantly changed. Taken together, these results suggest that deregulated gene expression caused by loss of Capds2 may cause developmental deficits and/or pathological symptoms, resulting in autistic-like phenotypes.

Sulfur dioxide (SO2 ) is a ubiquitous air pollutant. The previous studies have documented the adverse effects of SO2 on nervous system health, suggesting that acutely SO2 inhalation at high concentration may be associated with neurotoxicity and increase risk of hospitalization and mortality of many brain disorders. However, the remarkable features of air pollution exposure are lifelong duration and at low concentration; and it is rarely reported that whether there are different responses on synapse when rats inhaled same mass of SO2 at low concentration with a longer term. In this study, we evaluated the synaptic plasticity in rat hippocampus after exposure to same mass of SO2 at various concentrations and durations (3.5 and 7 mg/m(3) , 6 h/day, for 4 weeks; and 14 and 28 mg/m(3) , 6 h/day, for 1 week). The results showed that the mRNA level of synaptic plasticity marker Arc, glutamate receptors (GRIA1, GRIA2, GRIN1, GRIN2A, and GRIN2B) and the protein expression of memory related kinase p-CaMKпα were consistently inhibited by SO2 both in 1 week and 4 weeks exposure cases; the protein expression of presynaptic marker synaptophysin, postsynaptic density protein 95 (PSD-95), protein kinase A (PKA), and protein kinase C (PKC) were increased in 1 week exposure case, and decreased in 4 weeks exposure case. Our results indicated that SO2 inhalation caused differential synaptic injury in 1 week and 4 weeks exposure cases, and implied the differential effects might result from different PKA- and/or PKC-mediated signal pathway. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 820-829, 2016.

De novo GRIN variants, encoding for the ionotropic glutamate NMDA receptor subunits, have been recently associated with GRIN-related disorders (GRDs), a group of rare paediatric encephalopathies. Current investigational and clinical efforts are focused to functionally stratify GRIN variants, towards precision therapies of this primary disturbance of glutamatergic transmission that affects neuronal function and brain. In the present study, we aimed to comprehensively delineate the functional outcomes and clinical phenotypes of GRIN protein truncating variants (PTVs) -accounting for ~ 20% of disease-associated GRIN variants- hypothetically provoking NMDAR hypofunctionality. To tackle this question, we created a comprehensive GRIN PTVs variants database compiling a cohort of 9 individuals harbouring GRIN PTVs, together with previously identified variants, to build-up an extensive GRIN PTVs repertoire composed of 293 unique variants. Genotype-phenotype correlation studies were conducted, followed by cell-based assays of selected paradigmatic GRIN PTVs, allowing their functional annotation. Genetic and clinical phenotypes metaanalysis revealed that heterozygous GRIN1, GRIN2C, GRIN2D, GRIN3A and GRIN3B PTVs are non-pathogenic. In contrast, heterozygous GRIN2A and GRIN2B PTVs are associated with specific neurological clinical phenotypes in a subunit- and domain-dependent manner. Mechanistically, cell-based assays showed that paradigmatic pathogenic GRIN2A and GRIN2B PTVs result on a decrease of NMDAR surface expression and NMDAR-mediated currents, ultimately leading to NMDAR functional haploinsufficiency.. Overall, these findings contribute to delineate GRIN PTVs genotype-phenotype association, and GRIN variants stratification. Functional studies showed that GRIN2A and GRIN2B pathogenic PTVs trigger NMDAR hypofunctionality, and thus accelerate therapeutic decisions for this neurodevelopmental condition.

Age of onset (AO) of Huntington disease (HD) is mainly determined by the length of the CAG repeat expansion (CAGexp) in exon 1 of the HTT gene. Additional genetic variation has been suggested to contribute to AO, although the mechanism by which it could affect AO is presently unknown. The aim of this study is to explore the contribution of candidate genetic factors to HD AO in order to gain insight into the pathogenic mechanisms underlying this disorder. For that purpose, two AO definitions were used: the earliest age with unequivocal signs of HD (earliest AO or eAO), and the first motor symptoms age (motor AO or mAO). Multiple linear regression analyses were performed between genetic variation within 20 candidate genes and eAO or mAO, using DNA and clinical information of 253 HD patients from REGISTRY project. Gene expression analyses were carried out by RT-qPCR with an independent sample of 35 HD patients from Basque Country Hospitals. We found suggestive association signals between HD eAO and/or mAO and genetic variation within the E2F2, ATF7IP, GRIN2A, GRIN2B, LINC01559, HIP1 and GRIK2 genes. Among them, the most significant was the association between eAO and rs2742976, mapping to the promoter region of E2F2 transcription factor. Furthermore, rs2742976 T allele patient carriers exhibited significantly lower lymphocyte E2F2 gene expression, suggesting a possible implication of E2F2-dependent transcriptional activity in HD pathogenesis. Thus, E2F2 emerges as a new potential HD AO modifier factor.

N-methyl D-aspartate receptor subtype 2B (GluN2B), encoded by GRIN2B, is one of the components of the N-methyl D-aspartate receptor protein. Aberrations in GRIN2B have been reported to be responsible for various types of neurodevelopmental disorders. We report a Japanese boy with an ~2 Mb interstitial deletion in 12p13 involving the entire GRIN2B gene, who presented with intellectual disability, motor developmental delay and marked macrocephaly.

Hypoxia preconditioning is an effective strategy of intrinsic cell protection. An acute repetitive hypoxic mice model was developed. High-throughput microarray analysis was performed to explore the integrative alterations of gene expression in repetitive hypoxic mice. Data obtained was analyzed via multiple bioinformatics approaches to identify the hub genes, pathways and biological processes related to hypoxia preconditioning. The current study, for the first time, provides insights into the gene expression profiles in repetitive hypoxic mice. It was found that a total of 1175 genes expressed differentially between the hypoxic mice and normal mice. Overall, 113 significantly up-regulated and 138 significantly down-regulated functions were identified from the differentially expressed genes in repetitive hypoxic brains. Among them, at least fourteen of these genes were very associated with hypoxia preconditioning. The change trends of these genes were validated by reverse-transcription polymerase chain reaction and were found to be consistent with the microarray data. Combined the results of pathway and gene co-expression networks, we defined Plcb1, Cacna2d1, Atp2b4, Grin2a, Grin2b and Glra1 as the main hub genes tightly related with hypoxia preconditioning. The differential functions mainly included the mitogen-activated protein kinase pathway and ion or neurotransmitter transport. The multiple reactions in cell could be initiated by activating MAPK pathway to prevent hypoxia damage. Plcb1 was an important and hub gene and node in the hypoxia preconditioning signal networks. The findings in the hub genes and integrated gene networks provide very useful information for further exploring the molecular mechanisms of hypoxia preconditioning.

Genetic mutations are the major pathogenic factor of Autism Spectrum Disorder (ASD). In recent years, more and more ASD risk genes have been revealed, among which there are a group of transcriptional regulators. Considering the similarity of the core clinical phenotypes, it is possible that these different factors may regulate the expression levels of certain key targets. Identification of these targets could facilitate the understanding of the etiology and developing of novel diagnostic and therapeutic methods. Therefore, we performed integrated transcriptome analyses of RNA-Seq and microarray data in multiple ASD mouse models and identified a number of common downstream genes in various brain regions, many of which are related to the structure and function of the synapse components or drug addiction. We then established protein-protein interaction networks of the overlapped targets and isolated the hub genes by 11 algorithms based on the topological structure of the networks, including Sdc4, Vegfa, and Cp in the Cortex-Adult subgroup, Gria1 in the Cortex-Juvenile subgroup, and Kdr, S1pr1, Ubc, Grm2, Grin2b, Nrxn1, Pdyn, Grin3a, Itgam, Grin2a, Gabra2, and Camk4 in the Hippocampus-Adult subgroup, many of which have been associated with ASD in previous studies. Finally, we cross compared our results with human brain transcriptional data sets and verified several key candidates, which may play important role in the pathology process of ASD, including SDC4, CP, S1PR1, UBC, PDYN, GRIN2A, GABRA2, and CAMK4. In summary, by integrated bioinformatics analysis, we have identified a series of potentially important molecules for future ASD research. Autism Res 2019. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Abnormal transcriptional regulation accounts for a significant portion of Autism Spectrum Disorder. In this study, we performed transcriptome analyses of mouse models to identify common downstream targets of transcriptional regulators involved in ASD. We identified several recurrent target genes that are close related to the common pathological process of ASD, including SDC4, CP, S1PR1, UBC, PDYN, GRM2, NRXN1, GRIN3A, ITGAM, GRIN2A, GABRA2, and CAMK4. These results provide potentially important targets for understanding the molecular mechanism of ASD.

BACKGROUND

N-Methyl-D-aspartate receptors (NMDARs) play pivotal roles in synaptic development, plasticity, neural survival, and cognition. Despite recent reports describing the genetic association between de novo mutations of NMDAR subunits and severe psychiatric diseases, little is known about their pathogenic mechanisms and potential therapeutic interventions. Here we report a case study of a 4-year-old Rett-like patient with severe encephalopathy carrying a missense de novo mutation in GRIN2B(p.P553T) coding for the GluN2B subunit of NMDAR.

METHODS

We generated a dynamic molecular model of mutant GluN2B-containing NMDARs. We expressed the mutation in cell lines and primary cultures, and we evaluated the putative morphological, electrophysiological, and synaptic plasticity alterations. Finally, we evaluated D-serine administration as a therapeutic strategy and translated it to the clinical practice.

RESULTS

Structural molecular modeling predicted a reduced pore size of mutant NMDARs. Electrophysiological recordings confirmed this prediction and also showed gating alterations, a reduced glutamate affinity associated with a strong decrease of NMDA-evoked currents. Moreover, GluN2B(P553T)-expressing neurons showed decreased spine density, concomitant with reduced NMDA-evoked currents and impaired NMDAR-dependent insertion of GluA1 at stimulated synapses. Notably, the naturally occurring coagonist D-serine was able to attenuate hypofunction of GluN2B(p.P553T)-containing NMDARs. Hence, D-serine dietary supplementation was initiated. Importantly, the patient has shown remarkable motor, cognitive, and communication improvements after 17 months of D-serine dietary supplementation.

CONCLUSIONS

Our data suggest that hypofunctional NMDARs containing GluN2B(p.P553T) can contribute to Rett-like encephalopathy and that their potentiation by D-serine treatment may underlie the associated clinical improvement.

Approximately one-fourth of autism spectrum disorder (ASD) cases are associated with a disruptive genetic variant. Many of these ASD genotypes have been described previously, and are characterized by unique constellations of medical, psychiatric, developmental, and behavioral features. Development of precision medicine care for affected individuals has been challenging due to the phenotypic heterogeneity that exists even within each genetic subtype. In the present study, we identify developmental milestones that predict cognitive and adaptive outcomes for five of the most common ASD genotypes. Sixty-five youth with a known pathogenic variant involving ADNP, CHD8, DYRK1A, GRIN2B, or SCN2A genes participated in cognitive and adaptive testing. Exploratory linear regressions were used to identify developmental milestones that predicted cognitive and adaptive outcomes within each gene group. We hypothesized that the earliest and most predictive milestones would vary across gene groups, but would be consistent across outcomes within each genetic subtype. Within the ADNP group, age of walking predicted cognitive outcomes, while age of first words predicted adaptive behaviors. Age of phrases predicted adaptive functioning in the CHD8 group, but cognitive outcomes were not clearly associated with early developmental milestones. Verbal milestones were the strongest predictors of cognitive and adaptive outcomes for individuals with mutations to DYRK1A, GRIN2B, or SCN2A. These trends inform decisions about treatment planning and long-term expectations for affected individuals, and they add to the growing body of research linking molecular genetic function to brain development and phenotypic outcomes. LAY SUMMARY: Researchers have found many genetic causes of autism including mutations to ADNP, CHD8, DYRK1A, GRIN2B, and SCN2A genes. We found that each genetic cause had different early developmental milestones that explained the overall functioning of the children when they were older. Depending on the genetic cause, the age that a child first starts walking and/or talking may help to better understand and support a child's development who has a mutation to one of the above genes.

Keywords: developmental psychology; genetic/genomic syndromes; genetics; intellectual disability; subtypes of ASD.

D-Serine is an endogenous coagonist that increases the opening of N-methyl-D-aspartate (NMDA)-type glutamate receptor channels. We previously reported a reduction of D-serine serum levels in schizophrenia, supporting the disease hypothesis of NMDA receptor-mediated hypo-neurotransmission. The serum levels of D-serine are thought to reflect brain d-serine content. It is important to understand whether there is a direct link between the altered D-serine levels and NMDA receptor expression in vivo or whether these are independent processes. Two polymorphisms are known to regulate the expression of NMDA receptor subunit genes: (GT)(n) (rs3219790) in the promoter region of the NR2A subunit gene (GRIN2A) and -200T>> G (rs1019385) in the NR2B gene (GRIN2B). These polymorphisms are also reported to be associated with schizophrenia. Therefore, we examined the correlation between these two polymorphisms and d-serine serum levels in mentally healthy controls, schizophrenics and the combined group. We observed no significant genotype-phenotype correlations in any of the sample groups. However, analyses of larger sample numbers and the detection of additional polymorphisms that affect gene expression are needed before we can conclude that NMDA receptor expression and serum levels of d-serine, if involved in schizophrenia pathophysiology, are independent and additive events.

BACKGROUND

Glaucoma is characterized by optic neuropathy of the retinal ganglion cells (RGCs). Retinal ganglian cell death may be mediated by apoptosis. TP53 is involved in this process. It can also be found that excitotoxicity contributes to apoptosis by excess stimulation of glutamate receptors. The aim of this study was to evaluate the relationship of the TP53 (rs1042522) and GRIN2B (rs3764028) gene polymorphisms with risk of occurrence of primary open-angle glaucoma (POAG).

METHODS

The study population consisted of 186 patients and 188 healthy subjects. Genomic DNA was extracted from peripheral blood. Analysis of the gene polymorphisms was performed using PCR-RFLP.

RESULTS

Comparison of the distributions of genotypes and alleles of the rs1042522 and rs3764028 polymorphisms showed no statistically significant differences between POAG patients and controls (p>> 0.05). There was a statistically significant association of the rs1042522 polymorphism with progression of POAG depending on the retinal nerve fiber layer (p = 0.019). However, no significant differences between rs3764028 polymorphism and clinical parameters of POAG were observed (p>> 0.05).

CONCLUSIONS

The TP53 Arg72Pro and GRIN2B -421C/A gene polymorphisms were not associated with risk of occurrence of POAG in the Polish population. However, the Arg72Pro polymorphism of the TP53 gene may be related to progression of POAG.

Excess body weight is the main risk factor of type 2 diabetes. Recent studies have shown that psychological and behavioral factors affect weight. Additionally, emerging evidence indicates that polymorphisms of neurotransmitter genes can impact eating behavior. The aim of this study was to detect the associations between SNPs in glutamatergic system genes and type 2 diabetes in the ethnic group of Tatars origin living in the Republic of Bashkortostan (Russian Federation). In our case-control cross-sectional study, 501 patients with type 2 diabetes (170 men and 331 women, 60.9 ± 9.2 years old (mean ± SD), BMI 30.9 ± 3.9 kg/m² (mean ± SD) of Tatar ethnicity, and a control group of 420 Tatars (170 men and 250 women, 56.3 ± 11.6 years old (mean ± SD), BMI 24.4 ± 4.3 kg/m² (mean ± SD), were genotyped for five SNPs in four glutamatergic genes (GRIN2B, GRIK3, GRIA1, GRIN1). Three SNPs were associated with type 2 diabetes: rs7301328 in GRIN2B [odds ratio adjusted for age, sex and BMI (OR^adj) = 0.77 (95% CI 0.63-0.93), p^adj = 0.0077], rs1805476 in GRIN2B [OR^adj = 1.25 (95% CI 1.03-1.51), p^adj = 0.0240], and rs2195450 in GRIA1 [OR^adj = 1.35 (95% CI 1.02-1.79), p^adj = 0.0340]. Regression analysis revealed that rs1805476 in GRIN2B was associated with LDL level, glomerular filtration rate, BMI (p = 0.020, p = 0.012 and p = 0.018, respectively). The SNP rs7301328 in GRIN2B was associated with triglyceride levels and HbA_1c (p = 0.040, p = 0.023, respectively). These associations were not significant after Bonferroni correction. We found the association between rs534131 in GRIK3, rs2195450 in GRIA1, rs1805476 in GRIN2B and diabetic retinopathy (p = 0.005, p = 0.007, p = 0.040, respectively); rs7301328 in GRIN2B was associated with hypertension (p = 0.025) and cerebrovascular disease (p = 0.013). The association between rs534131 of GRIK3, rs2195450 of GRIA1 genes and diabetic retinopathy remained significant after Bonferroni correction. The SNPs rs6293 in GRIN1 was significantly associated with eating behavior in patients with type 2 diabetes (p = 0.01). Our results demonstrate that polymorphic variants of glutamatergic genes are associated with eating behavior and diabetic complications in Tatar ethnic group residing in the Republic of Bashkortostan. We detected novel associations of the polymorphic loci in GRIN1 (rs6293) gene with external eating behavior in type 2 diabetes patients, GRIK3 (rs534131) and GRIA1 (rs2195450) genes with diabetic retinopathy.

The concept of frailty has been used in the clinical and research field for more than two decades. It is usually described as a clinical state of heightened vulnerability to poor resolution of homeostasis after a stressor event, which thereby increases the risk of adverse outcomes, including falls, delirium, disability and mortality. Here we report the results of the first genome-wide association scan and comparative gene ontology analyses where we aimed to identify genes and pathways associated with the deficit model of frailty. We used a discovery-replication design with two independent, nationally representative samples of older adults. The square-root transformed Frailty Index (FI) was the outcome variable, and age and sex were included as covariates. We report one hit exceeding genome-wide significance: the rs6765037 A allele was significantly associated with a decrease in the square-root transformed FI score in the Discovery sample (beta = -0.01958, p = 2.14E-08), without confirmation in the Replication sample. We also report a nominal replication: the rs7134291 A allele was significantly associated with a decrease in the square-root transformed FI score (Discovery sample: beta = -0.01021, p = 1.85E-06, Replication sample: beta = -0.005013, p = 0.03433). These hits represent the KBTBD12 and the GRIN2B genes, respectively. Comparative gene ontology analysis identified the pathways 'Neuropathic pain signalling in dorsal horn neurons' and the 'GPCR-Mediated Nutrient Sensing in Enteroendocrine Cells', exceeding the p = 0.01 significance in both samples, although this result does not survive correction for multiple testing. Considering the crucial role of GRIN2B in brain development, synaptic plasticity and cognition, this gene appears to be a potential candidate to play a role in frailty. In conclusion, we conducted genome-wide association scan and pathway analyses and have identified genes and pathways with potential roles in frailty. However, frailty is a complex condition. Therefore, further research is required to confirm our results and more thoroughly identify relevant biological mechanisms.

Systemic lupus erythematosus (SLE) is a complex disorder. Genetic association studies of complex disorders suffer from the following three major issues: phenotypic heterogeneity, false positive (type I error), and false negative (type II error) results. Hence, genes with low to moderate effects are missed in standard analyses, especially after statistical corrections. OASIS is a novel linkage disequilibrium clustering algorithm that can potentially address false positives and negatives in genome-wide association studies (GWAS) of complex disorders such as SLE. OASIS was applied to two SLE dbGAP GWAS datasets (6077 subjects; ∼0.75 million single-nucleotide polymorphisms). OASIS identified three known SLE genes viz. IFIH1, TNIP1, and CD44, not previously reported using these GWAS datasets. In addition, 22 novel loci for SLE were identified and the 5 SLE genes previously reported using these datasets were verified. OASIS methodology was validated using single-variant replication and gene-based analysis with GATES. This led to the verification of 60% of OASIS loci. New SLE genes that OASIS identified and were further verified include TNFAIP6, DNAJB3, TTF1, GRIN2B, MON2, LATS2, SNX6, RBFOX1, NCOA3, and CHAF1B. This study presents the OASIS algorithm, software, and the meta-analyses of two publicly available SLE GWAS datasets along with the novel SLE genes. Hence, OASIS is a novel linkage disequilibrium clustering method that can be universally applied to existing GWAS datasets for the identification of new genes.

Autism spectrum disorder (ASD) is a complex disorder with an unclear aetiology and an estimated global prevalence of 1%. However, studies of ASD in the Vietnamese population are limited. Here, we first conducted whole exome sequencing (WES) of 100 children with ASD and their unaffected parents. Our stringent analysis pipeline was able to detect 18 unique variants (8 de novo and 10 ×-linked, all validated), including 12 newly discovered variants. Interestingly, a notable number of X-linked variants were detected (56%), and all of them were found in affected males but not in affected females. We uncovered 17 genes from our ASD cohort in which CHD8, DYRK1A, GRIN2B, SCN2A, OFD1 and MDB5 have been previously identified as ASD risk genes, suggesting the universal aetiology of ASD for these genes. In addition, we identified six genes that have not been previously reported in any autism database: CHM, ENPP1, IGF1, LAS1L, SYP and TBX22. Gene ontology and phenotype-genotype analysis suggested that variants in IGF1, SYP and LAS1L could plausibly confer risk for ASD. Taken together, this study adds to the genetic heterogeneity of ASD and is the first report elucidating the genetic landscape of ASD in Vietnamese children.

Detection of chromosomal translocation is a key component in diagnosis and management of acute myeloid leukemia (AML). Targeted RNA next-generation sequencing (NGS) is emerging as a powerful and clinically practical tool, but it depends on expression of RNA transcript from the underlying DNA translocation. Here, we show the clinical utility of nanopore long-read sequencing in rapidly detecting DNA translocation with exact breakpoints. In a newly diagnosed patient with AML, conventional karyotyping showed translocation t(10;12)(q22;p13) but RNA NGS detected NUP98-NSD1 fusion transcripts from a known cryptic translocation t(5;11)(q35;p15). Rapid PCR-free nanopore whole-genome sequencing yielded a 26,194 bp sequencing read and revealed the t(10;12) breakpoint to be DUSP13 and GRIN2B in head-to-head configuration. This translocation was then classified as a passenger structural variant. The sequencing also yielded a 20,709 bp sequencing read and revealed the t(5;11) breakpoint of the driver NUP98-NSD1 fusion. The identified DNA breakpoints also served as markers for molecular monitoring, in addition to fusion transcript expression by digital PCR and sequence mutations by NGS. We illustrate that third-generation nanopore sequencing is a simple and low-cost workflow for DNA translocation detection.

Aim: We investigated: Grin1, Grin2a, Grin2b DNA methylation; NR1 and NR2 mRNA/protein in the prefrontal cortex (PFC); and hippocampus of male Wistar rats exposed to isolation rearing. Materials & methods: Animals were kept isolated or grouped (n = 10/group) from weaning for 10 weeks. Tissues were dissected for RNA/DNA extraction and N-methyl-D-aspartate receptor subunits were analyzed using quantitative reverse transcription (RT)-PCR, ELISA and pyrosequencing. Results: Isolated-reared animals had: decreased mRNA in PFC for all markers, increased NR1 protein in hippocampus and hypermethylation of Grin1 in PFC and Grin2b in hippocampus, compared with grouped rats. Associations between mRNA/protein and DNA methylation were found for both brain areas. Conclusion: This study indicates that epigenetic DNA methylation may underlie N-methyl-D-aspartate receptor mRNA/protein expression alterations caused by isolation rearing.

Keywords: DNA methylation; NMDAR; early stress; gene expression; glutamate receptor; hippocampus; isolation rearing from weaning; prefrontal cortex; protein expression; schizophrenia.

Autosomal recessive ataxia telangiectasia (A-T) is characterized by radiosensitivity, immunodeficiency, and cerebellar neurodegeneration. A-T is caused by inactivating mutations in the ataxia telangiectasiamutated (ATM) gene, a serine-threonine protein kinase involved in DNA damage response and excitatory neurotransmission. The selective vulnerability of cerebellar Purkinje neurons (PN) to A-T is not well understood. Employing global proteomic profiling of cerebrospinal fluid from patients at ages around 15 years, we detected reduced calbindin, reelin, cerebellin-1, cerebellin-3, protocadherin fat 2, sempahorin 7A, and increased apolipoprotein B and J peptides. Bioinformatic enrichment was observed for pathways of lipoproteins, endocytosis, extracellular matrix receptor interaction, peptidase activity, adhesion, calcium binding, and complement immunity. This seemed important since secretion of reelin from glutamatergic afferent axons is crucial for PN lipoprotein receptor endocytosis and lipid signaling. Reelin expression is downregulated by irradiation and reelin/ApoB mutations are known causes of ataxia. Validation efforts in 2-month-old Atm-/- mice before onset of motor deficits confirmed cerebellar transcript reductions for reelin receptors Apoer2/Vldlr with increases for their ligands Apoe/Apoh and cholesterol 24-hydroxylase Cyp46a1. Concomitant dysregulations were found for Vglut2/Sema7a as climbing fiber markers, glutamate receptors like Grin2b, and calcium homeostasis factors (Atp2b2, Calb1, Itpr1), while factors involved in DNA damage, oxidative stress, neuroinflammation, and cell adhesion were normal at this stage. Quantitative immunoblots confirmed ApoB and ApoJ increases and VLDLR reduction in cerebellar tissue at the age of 2 months. These findings show that ApoB excess and reelin signaling deficits reflect the neurodegeneration in A-T in a sensitive and specific way. As extracellular factors, apolipoproteins and their cargo such as vitamin E may be useful for neuroprotective interventions.