Deep exome sequencing identifies enrichment of deleterious mosaic variants in neurodevelopmental disorder genes and mitochondrial tRNA regions in bipolar disorder.

Bipolar disorder (BD) is a global medical issue, afflicting around 1% of the population with manic and depressive episodes. Despite various genetic studies, the genetic architecture and pathogenesis of BD have not been fully resolved. Besides germline variants, postzygotic mosaic variants are proposed as new candidate mechanisms contributing to BD. Here, we performed extensive deep exome sequencing (DES, ~300×) and validation experiments to investigate the roles of mosaic variants in BD with 235 BD cases (194 probands of trios and 41 single cases) and 39 controls. We found an enrichment of developmental disorder (DD) genes in the genes hit by deleterious mosaic variants in BD (P = 0.000552), including a ClinVar-registered pathogenic variant in ARID2. An enrichment of deleterious mosaic variants was also observed for autism spectrum disorder (ASD) genes (P = 0.000428). The proteins coded by the DD/ASD genes with non-synonymous mosaic variants in BD form more protein-protein interaction than expected, suggesting molecular mechanisms shared with DD/ASD but restricted to a subset of cells in BD. We also found significant enrichment of mitochondrial heteroplasmic variants, another class of mosaic variants, in mitochondrial tRNA genes in BD (P = 0.0102). Among them, recurrent m.3243 A > G variants known as causal for mitochondrial diseases were found in two unrelated BD probands with allele fractions of 5-12%, lower than in mitochondrial diseases. Despite the limitation of using peripheral tissues, our DES investigation supports the possible contribution of deleterious mosaic variants in the nuclear genome responsible for severer phenotypes, such as DD/ASD, to the risk of BD and further demonstrates that the same paradigm can be applied to the mitochondrial genome. These results, as well as the enrichment of heteroplasmic mitochondrial tRNA variants in BD, add a new piece to the understanding of the genetic architecture of BD and provide general insights into the pathological roles of mosaic variants in human diseases.

Somatic mutations in the human brain: implications for psychiatric research.

Psychiatric disorders such as schizophrenia and bipolar disorder are caused by complex gene-environment interactions. While recent advances in genomic technologies have enabled the identification of several risk variants for psychiatric conditions, including single-nucleotide variants and copy-number variations, these factors can explain only a portion of the liability to these disorders. Although non-inherited factors had previously been attributed to environmental causes, recent genomic analyses have demonstrated that de novo mutations are among the main non-inherited risk factors for several psychiatric conditions. Somatic mutations in the brain may also explain how stochastic developmental events and environmental insults confer risk for a psychiatric disorder following fertilization. Here, we review evidence regarding somatic mutations in the brains of individuals with and without neuropsychiatric diseases. We further discuss the potential biological mechanisms underlying somatic mutations in the brain as well as the technical issues associated with the detection of somatic mutations in psychiatric research.

Mutations of the glycine cleavage system genes possibly affect the negative symptoms of schizophrenia through metabolomic profile changes.

AIM: Hypofunction of N-methyl-D-aspartate receptors (NMDAR) may contribute to the pathophysiology of schizophrenia (SCZ). Recently, the glycine cleavage system (GCS) was shown to affect NMDAR function in the brain. GCS functional defects cause nonketotic hyperglycinemia, the atypical phenotype of which presents psychiatric symptoms similar to SCZ. Here, we examined the involvement of GCS in SCZ. METHODS: First, to identify the rare variants and the exonic deletions, we resequenced all the coding exons and the splice sites of four GCS genes (GLDC, AMT, GCSH, and DLD) in 474 patients with SCZ and 475 controls and performed multiplex ligation-dependent probe amplification analysis in SCZ. Next, we performed metabolome analysis using plasma of patients harboring GCS variants (n = 5) and controls (n = 5) by capillary electrophoresis time-of-flight mass spectrometry. The correlation between plasma metabolites and Positive and Negative Syndrome Scale score was further examined. RESULTS: Possibly damaging variants were observed in SCZ: A203V, S801N in GLDC, near the atypical nonketotic hyperglycinemia causative mutations (A202V, A802V); G825D in GLDC, a potential neural tube defect causative mutation; and R253X in AMT. Marked elevation of plasma 5-oxoproline (pyroglutamic acid), aspartate, and glutamate, which might affect NMDAR function, was observed in patients harboring GCS variants. The aspartate level inversely correlated with negative symptoms (r = -0.942, P = 0.0166). CONCLUSION: These results suggest that GCS rare variants possibly contribute to the pathophysiology of SCZ by affecting the negative symptoms through elevation of aspartate.

Identification of somatic mutations in postmortem human brains by whole genome sequencing and their implications for psychiatric disorders.

AIM: Somatic mutations in the human brain are hypothesized to contribute to the functional diversity of brain cells as well as the pathophysiology of neuropsychiatric diseases. However, there are still few reports on somatic mutations in non-neoplastic human brain tissues. This study attempted to unveil the landscape of somatic mutations in the human brain. METHODS: We explored the landscape of somatic mutations in human brain tissues derived from three individuals with no neuropsychiatric diseases by whole-genome deep sequencing at a depth of around 100. The candidate mutations underwent multi-layered filtering, and were validated by ultra-deep target amplicon sequencing at a depth of around 200 000. RESULTS: Thirty-one somatic mutations were identified in the human brain, demonstrating the utility of whole-genome sequencing of bulk brain tissue. The mutations were enriched in neuron-expressed genes, and two-thirds of the identified somatic single nucleotide variants in the brain tissues were cytosine-to-thymine transitions, half of which were in CpG dinucleotides. CONCLUSION: Our developed filtering and validation approaches will be useful to identify somatic mutations in the human brain. The vulnerability of neuron-expressed genes to mutational events suggests their potential relevance to neuropsychiatric diseases.

Detection of resting state functional connectivity using partial correlation analysis: A study using multi-distance and whole-head probe near-infrared spectroscopy.

Multichannel near-infrared spectroscopy (NIRS) is a functional neuroimaging modality that enables easy-to-use and noninvasive measurement of changes in blood oxygenation levels. We developed a clinically-applicable method for estimating resting state functional connectivity (RSFC) with NIRS using a partial correlation analysis to reduce the influence of extraneural components. Using a multi-distance probe arrangement NIRS, we measured resting state brain activity for 8min in 17 healthy participants. Independent component analysis was used to extract shallow and deep signals from the original NIRS data. Pearson's correlation calculated from original signals was significantly higher than that calculated from deep signals, while partial correlation calculated from original signals was comparable to that calculated from deep (cerebral-tissue) signals alone. To further test the validity of our method, we also measured 8min of resting state brain activity using a whole-head NIRS arrangement consisting of 17 cortical regions in 80 healthy participants. Significant RSFC between neighboring, interhemispheric homologous, and some distant ipsilateral brain region pairs was revealed. Additionally, females exhibited higher RSFC between interhemispheric occipital region-pairs, in addition to higher connectivity between some ipsilateral pairs in the left hemisphere, when compared to males. The combined results of the two component experiments indicate that partial correlation analysis is effective in reducing the influence of extracerebral signals, and that NIRS is able to detect well-described resting state networks and sex-related differences in RSFC.

A case of thyroid storm with a markedly elevated level of circulating soluble interleukin-2 receptor complicated by multiple organ failure and disseminated intravascular coagulation syndrome.

Thyroid storm (TS) is a life-threatening endocrine emergency. However, the pathogenesis of TS is poorly understood. A 40-year-old man was admitted to a nearby hospital with body weight loss and jaundice. Five days after a contrasted abdominal computerized tomography (CT) scan, he exhibited high fever and disturbance of consciousness. He was diagnosed with TS originating from untreated Graves' disease and was transferred to the intensive care unit (ICU) of our hospital. The patient exhibited impaired consciousness (E4V1M4 in Glasgow coma scale), high fever (39.3°C), and atrial flutter with a pulse rate 162/min, and was complicated by heart failure, acute hepatic failure, and disseminated intravascular coagulation syndrome (DIC). His circulating level of soluble interleukin-2 receptor (sIL-2R), a serum marker of an activated immune response, was highly elevated (7,416 U/mL, reference range: 135-483). Multiple organ failure (MOF) and DIC were successfully managed by multimodality treatments using inorganized iodide, glucocorticoids, anti-thyroid drugs, beta-blockers, and diuretics as well as an anticoagulant agent and the transfusion of platelet concentrate and fresh frozen plasma. sIL-2R levels gradually decreased during the initial treatment, but were still above the reference range even after thyroidectomy. Mild elevations in serum levels of sIL-2R have previously been correlated with thyroid hormone levels in non-storm Graves' disease. The present study demonstrated, for the first time, that circulating sIL-2R levels could be markedly elevated in TS. The marked increase in sIL-2R levels was speculated to represent an inappropriate generalized immune response that plays an unknown role in the pathogenesis of TS.

Comprehensive DNA methylation analysis of peripheral blood cells derived from patients with first-episode schizophrenia.

Epidemiological studies have revealed that schizophrenia is highly heritable. However, genetic studies have not fully elucidated its etiology. Accumulating evidence suggests that epigenetic alterations may provide an additional explanation of its pathophysiology. We investigated the methylation profiles of DNA in peripheral blood cells from 18 patients with first-episode schizophrenia (FESZ) and from 15 normal controls. Schizophrenia patients were confined to those at the stage of first-episode psychosis. We analyzed the DNA methylation status of 27,578 CpG sites by means of the Illumina Infinium HumanMethylation27 BeadChip array. Differentially methylated CpG sites, which were particularly abundant within CpG islands, were enriched in genes related to the nuclear lumen, to transcription factor binding, and to nucleotide binding. We also observed differential methylation of the promoters of HTR1E and COMTD1, which are functionally related to genes found to be differentially methylated in schizophrenia patients in previous studies. Our results indicate the site-specific epigenetic alterations in patients with FESZ.

[Current status of epigenetics of schizophrenia].

The patients with schizophrenia suffer from a lot of severe symptoms; positive symptoms, negative symptoms and cognitive impairment. However, the pathophysiology remains almost unknown, and no curative therapy is available for the patients. Thus, the elucidation of the pathophysiology and development of curative therapy are imperative. Epigenetics is a promising approach in that it can explain the environmental effects as well as gene-environmental interaction. Here, we review the recent progress of epigenetic studies in relation to schizophrenia and discuss the limitation of previous studies. Epigenetic studies applying the recent progress of genomics and neuroscience will contribute to better understanding of schizophrenia pathophysiology and the development of therapeutic strategy.

The Current Progress of Psychiatric Genomics.

Psychiatric disorders such as bipolar disorder and schizophrenia are highly heritable. While the genetic contribution to psychiatric disorders is quite sure, specific genetic factors contributing to particular conditions have long been a mystery. Empowered by the initial report of the Human Genome Project, the analysis of the comprehensive set of the human genome, called "genomics," became possible. Subsequent development of large-scale genomic technologies enabled us to elucidate various disease-related genetic information, accelerating our understanding of various diseases. Genomic research on psychiatric disorders is not an exception. In this Review, I introduce significant advancements in psychiatric genomics with a special focus on our investigation of bipolar disorder. International consortiums and advocacy groups accelerate psychiatric genomics, increasing the sample size and statistical power for robust findings. The genetic architecture of schizophrenia has been elucidated in both common and rare variant studies. The genetic architecture of autism spectrum disorder (ASD) has been elucidated mainly by rare variant analysis. As to bipolar disorder, common variant analysis precedes rare variant analysis, but we are struggling to elucidate relevant rare variants. While the genomic approach has explained specific genetic factors for particular disorders, overlapping risk genes or pleiotropy has been observed more than expected. The boundary in the current nosology of psychiatric disorders is more or less challenged. To understand the genotype-phenotype relation more deeply, an attempt to understand phenotypes based on genotypes, called the "genotype first" approach, has started. I discuss this new approach for better understanding and treatment of psychiatric disorders.

Identification of 22q11.2 deletion in a patient with schizophrenia and clinically diagnosed Rubinstein-Taybi syndrome.

Background: Rubinstein-Taybi syndrome (RTS) is a rare autosomal-dominant disease. Almost all cases are sporadic and attributed to de novo variant. Psychotic symptoms in RTS are rare and have been reported in only a few published cases. On the other hand, 22q11.2 deletion syndrome is the most common chromosomal microdeletion in humans. The 22q11.2 deletion is well recognized as a risk factor for schizophrenia. Here, we present a schizophrenic psychosis case clinically diagnosed as RTS but resolved as carrying 22q11.2 deletion by genomic analysis. Case presentation: A 38-year-old Japanese male was admitted to our hospital due to psychotic symptoms. He had been diagnosed with RTS based on physical characteristics at the age of 9 months. On admission, we performed whole exome sequencing. He had no pathogenic variant in CREBBP or EP300. We detected 2.5 Mb deletion on 22q11.2 and one rare loss-of-function variant in a loss-of-function-constrained gene (MTSS1) and three rare missense variants in missense-constrained genes (CELSR3, HERC1, and TLN1). Psychotic symptoms were ameliorated by the treatment of risperidone. Conclusion: The psychiatric manifestation and genomic analysis may be a clue to detecting 22q11.2 deletion syndrome in undiagnosed patients. The reason for similarity in physical characteristics in 22q11.2 deletion syndrome and RTS remains unresolved. The 22q11.2 deletion and HERC1 contribute to the patient's phenotype.

Systematic analysis of exonic germline and postzygotic de novo mutations in bipolar disorder.

Bipolar disorder is a severe mental illness characterized by recurrent manic and depressive episodes. To better understand its genetic architecture, we analyze ultra-rare de novo mutations in 354 trios with bipolar disorder. For germline de novo mutations, we find significant enrichment of loss-of-function mutations in constrained genes (corrected-P = 0.0410) and deleterious mutations in presynaptic active zone genes (FDR = 0.0415). An analysis integrating single-cell RNA-sequencing data identifies a subset of excitatory neurons preferentially expressing the genes hit by deleterious mutations, which are also characterized by high expression of developmental disorder genes. In the analysis of postzygotic mutations, we observe significant enrichment of deleterious ones in developmental disorder genes (P = 0.00135), including the SRCAP gene mutated in two unrelated probands. These data collectively indicate the contributions of both germline and postzygotic mutations to the risk of bipolar disorder, supporting the hypothesis that postzygotic mutations of developmental disorder genes may contribute to bipolar disorder.

Altered expression of microRNA-223 in the plasma of patients with first-episode schizophrenia and its possible relation to neuronal migration-related genes.

Recent studies have shown that microRNAs (miRNAs) play a role as regulators of neurodevelopment by modulating gene expression. Altered miRNA expression has been reported in various psychiatric disorders, including schizophrenia. However, the changes in the miRNA expression profile that occur during the initial stage of schizophrenia have not been fully investigated. To explore the global alterations in miRNA expression profiles that may be associated with the onset of schizophrenia, we first profiled miRNA expression in plasma from 17 patients with first-episode schizophrenia and 17 healthy controls using microarray analysis. Among the miRNAs that showed robust changes, the elevated expression of has-miR-223-3p (miR-223) was validated via quantitative reverse transcription-polymerase chain reaction (qRT-PCR) using another independent sample set of 21 schizophrenia patients and 21 controls. To identify the putative targets of miR-223, we conducted a genome-wide gene expression analysis in neuronally differentiated SK-N-SH cells with stable miR-223 overexpression and an in silico analysis. We found that the mRNA expression levels of four genes related to the cytoskeleton or cell migration were significantly downregulated in miR-223-overexpressing cells, possibly due to interactions with miR-223. The in silico analysis suggested the presence of miR-223 target sites in these four genes. Lastly, a luciferase assay confirmed that miR-223 directly interacted with the 3' untranslated regions (UTRs) of all four genes. Our results reveal an increase in miR-223 in plasma during both the first episode and the later stage of schizophrenia, which may affect the expression of cell migration-related genes targeted by miR-223.

Novel rare variations in genes that regulate developmental change in N-methyl-d-aspartate receptor in patients with schizophrenia.

The mechanism underlying the vulnerability to developing schizophrenia (SCZ) during adolescence remains elusive. Hypofunction of N-methyl-d-aspartate receptors (NMDARs) has been implicated in the pathophysiology of SCZ. During development, the composition of synaptic NMDARs dramatically changes from NR2B-containing NMDARs to NR2A-containing NMDARs through the phosphorylation of NR2B S1480 or Y1472 by CDK5, CSNK2A1, and EphB2, which plays a pivotal role in the maturation of neural circuits. We hypothesized that the dysregulation of developmental change in NMDARs could be involved in the onset of SCZ. Using next-generation sequencing, we re-sequenced all the coding regions and splice sites of CDK5, CSNK2A1, and EphB2 in 474 patients with SCZ and 475 healthy controls. Variants on the database for human control subjects of Japanese origin were removed and all the nonsynonymous and nonsense variants were validated using Sanger sequencing. Four novel variants in CDK5 were observed in patients with SCZ but were not observed in controls. The total number of variants, however, was not significantly different between the SCZ and control groups (P=0.062). In silico analyses predicted P271T to be damaging. Further genetic research using a larger sample is required to examine whether CDK5 is involved in the pathophysiology of SCZ.

Identification of somatic mutations in monozygotic twins discordant for psychiatric disorders.

Monozygotic twins are assumed to have identical genomes. Based on this assumption, phenotypic discordance in monozygotic twins has been previously attributed to environmental factors. However, recent genomic studies have identified characteristic somatic mutations in monozygotic twins discordant for Darier disease, Van der Woude syndrome, and Dravet syndrome. Here, we explored somatic mutations in four pairs of monozygotic twins discordant for schizophrenia or delusional disorder. We analyzed whole exome sequence data obtained from blood samples and identified seven somatic mutations in one twin pair discordant for delusional disorder. All seven of these mutations were validated by independent amplicon sequencing, and five of them were further validated by pyrosequencing. One somatic mutation in the patient with delusional disorder showed a missense variant in ABCC9 with an allele fraction of 7.32%. Although an association between the somatic mutations and phenotypic discordance could not be established conclusively in this study, our results suggest that somatic mutations in monozygotic twins may contribute to the development of psychiatric disorders, and can serve as high-priority candidates for genetic studies.

Adrenal Ewing's Sarcoma in an Elderly Man.

Ewing's sarcoma usually arises in the bones of children and adolescents. We herein report a 74-year-old man with Ewing's sarcoma in the adrenal gland. The diagnosis was confirmed by a genetic test, pathological studies, and several imaging studies. He already had multiple liver metastases when he was transferred to our hospital and died on the 37th day. The diagnosis was further confirmed by autopsy studies. Adrenal Ewing's sarcoma is very rare, and our patient was older than other reported cases. Ewing's sarcoma should be considered even in elderly patients with adrenal tumors.

p53 and MIB-1 expression of esophageal carcinoma concominant with achalasia.

Achalasia, insufficient relaxation of the lower esophageal sphincter (LES) causes the retention and stasis of food and secretions, chronic hyperplastic esophagitis and eventual malignant transformation. p53 alternation has been suggested to play an important role in the malignant transformation. A 53-year-old man was endoscopically followed up for esophageal achalasia for seven years, and endoscopy revealed an ulcerative region in the upper thoracic esophagus, and histopathologically the biopsy specimens showed moderately differentiated squamous cell carcinoma. In resected specimens, p53 staining was strong and diffuse in the tumor and MIB-1 immunoreactivity was strong and patchy in the tumor and the basal layer of squamous mucosa of the esophagus. No staining for either immunostains was noted in normal esophageal mucosa. It is necessary for patients with esophageal achalasia to be followed-up with endoscopy, and that p53 and MIB-1 immunostaining of biopsy specimens should be performed to detect pre-cancerous lesions.

[A case of advanced rectal cancer responding to 5-fluorouracil based preoperative chemoradiation therapy].

We report a case of a 67-year-old female with advanced rectal cancer that showed a significant response after administration of preoperative chemoradiation therapy. 5-fluorouracil (5-FU, 300 mg/m2/day) was administered by 24-hour continuous intravenous infusion after the cancer had been decreased in size by radiation (2 Gy) administered for 20 days preoperatively. Consequently, the patient underwent a low anterior resection with lymph node dissection (D 2), which resulted in a curative resection of the cancer cells macroscopically. Histological examination revealed no residual cancer cells in the resected specimen (CR). Preoperative chemoradiation therapy appears a promising regimen for patients with advanced lower rectal cancer, and can be considered to extend the indication for laparoscopic operations for advanced rectal cancer.

Using social epidemiology and neuroscience to explore the relationship between job stress and frontotemporal cortex activity among workers.

Mental health problems, such as depression, are increasingly common among workers. Job-related stresses, including psychological demands and a lack of discretion in controlling one's own work environment, are important causal factors. However, the mechanisms through which job-related stress may affect brain function remain unknown. We sought to identify the relationship between job-related stress and frontotemporal cortex activation using near-infrared spectroscopy. Seventy-nine (45 females, 34 males) Japanese employees, aged 26-51 years, were recruited from respondents to the Japanese Study of Stratification, Health, Income, and Neighborhood survey. Job-related stress was measured using the Japanese version of Job Content Questionnaire, which can index "job demand" and "job control". We found a significant correlation between higher "job demand" and smaller oxygenated hemoglobin [oxy-Hb] changes in the left dorsolateral prefrontal cortex in female (r = -.54 to -.44). Significant correlations between higher "job control" and greater [oxy-Hb] changes in the right temporal cortex were observed among male, and in the combined sample (r = .46-.64). This initial cross-sectional observation suggests that elevated job-related stress is related to decrease frontotemporal cortex activation among workers. Integrating social epidemiology and neuroscience may be a powerful strategy for understanding how individuals' brain functions may mediate between the job-related stress or psychosocial work characteristics and public mental health.

Comprehensive DNA methylation analysis of human neuroblastoma cells treated with blonanserin.

Blonanserin is a second-generation antipsychotic drug for schizophrenia. The pharmacological actions of blonanserin are shown to be the antagonism of dopamine receptor 2 and serotonin receptors. However, its molecular mechanisms in brain cells have not been fully characterized. Accumulating evidence suggests that antipsychotic drugs and mood stabilizers show epigenetic effects on a wide range of genes in animal and cellular models. We performed genome-wide DNA methylation analysis targeting 479,814 CpG sites of cultured human neuroblastoma cells administered with blonanserin. We found that 3,057 CpG sites showed statistically significant changes in DNA methylation at two different doses of blonanserin (1.36 nM and 13.6 nM). These included hypermethylated CpG sites that were enriched in genes related to axonogenesis and cell morphogenesis involved in neuron differentiation. We also showed that the global effect on DNA methylome depends on the concentration of the drug. With a high dose of blonanserin, the overall methylation levels across all CpG sites significantly increased. These increases in DNA methylation were prominent in the CpG sites distant from promoter regions. We further examined DNA methylation changes in specific genes implicated for the actions of antipsychotic drugs, such as the dopamine receptor 2 (DRD2) gene and the serotonin receptor 2A (HTR2A) gene. We observed that CpG sites that were located within DRD2 and HTR2A genes were significantly hypermethylated by blonanserin. The DNA methylation changes induced by the treatment with blonanserin will be useful for understanding its pharmacological actions at the cellular level.

WITHDRAWN: Neuronal cell-type specific DNA methylation patterns of the Cacna1cgene.

The Publisher regrets that this article is an accidental duplication of an articlethat has already been published, http://dx.doi.org/10.1016/j.ijdevneu.2012.11.007. The duplicate article has therefore been withdrawn.