The genetic architecture of schizophrenia: review of large-scale genetic studies.

Schizophrenia is a complex and often chronic psychiatric disorder with high heritability. Diagnosis of schizophrenia is still made clinically based on psychiatric symptoms; no diagnostic tests or biomarkers are available. Pathophysiology-based diagnostic scheme and treatments are also not available. Elucidation of the pathogenesis is needed for development of pathology-based diagnostics and treatments. In the past few decades, genetic research has made substantial advances in our understanding of the genetic architecture of schizophrenia. Rare copy number variations (CNVs) and rare single-nucleotide variants (SNVs) detected by whole-genome CNV analysis and whole-genome/-exome sequencing analysis have provided the great advances. Common single-nucleotide polymorphisms (SNPs) detected by large-scale genome-wide association studies have also provided important information. Large-scale genetic studies have been revealed that both rare and common genetic variants play crucial roles in this disorder. In this review, we focused on CNVs, SNVs, and SNPs, and discuss the latest research findings on the pathogenesis of schizophrenia based on these genetic variants. Rare variants with large effect sizes can provide mechanistic hypotheses. CRISPR-based genetics approaches and induced pluripotent stem cell technology can facilitate the functional analysis of these variants detected in patients with schizophrenia. Recent advances in long-read sequence technology are expected to detect variants that cannot be detected by short-read sequence technology. Various studies that bring together data from common variant and transcriptomic datasets provide biological insight. These new approaches will provide additional insight into the pathophysiology of schizophrenia and facilitate the development of pathology-based therapeutics.

Sequencing of selected chromatin remodelling genes reveals increased burden of rare missense variants in ASD patients from the Japanese population.

Chromatin remodelling is an important process in neural development and is related to autism spectrum disorder (ASD) and schizophrenia (SCZ) aetiology. To further elucidate the involvement of chromatin remodelling genes in the genetic aetiology of ASD and SCZ in the Japanese population, we performed a case-control study. Targeted sequencing was conducted on coding regions of four BAF chromatin remodelling complex genes: SMARCA2, SMARCA4, SMARCC2, and ARID1B in 185 ASD, 432 SCZ patients, and 517 controls. 27 rare non-synonymous variants were identified in ASD and SCZ patients, including 25 missense, one in-frame deletion in SMRACA4, and one frame-shift variant in SMARCC2. Association analysis was conducted to investigate the burden of rare variants in BAF genes in ASD and SCZ patients. Significant enrichment of rare missense variants in BAF genes, but not synonymous variants, was found in ASD compared to controls. Rare pathogenic variants indicated by in silico tools were significantly enriched in ASD, but not statistically significant in SCZ. Pathogenic-predicted variants were located in disordered binding regions and may confer risk for ASD and SCZ by disrupting protein-protein interactions. Our study supports the involvement of rare missense variants of BAF genes in ASD and SCZ susceptibility.

Contribution of copy number variations to the risk of severe eating disorders.

AIM: Eating disorders (EDs) are complex, multifactorial psychiatric conditions. Previous studies identified pathogenic copy number variations associated with NDDs (NDD-CNVs) in ED patients. However, no statistical evidence for an association between NDD-CNVs and EDs has been demonstrated. Therefore, we examined whether NDD-CNVs confer risk for EDs. METHODS: Using array comparative genomic hybridization (aCGH), we conducted a high-resolution CNV analysis of 71 severe female ED patients and 1045 female controls. According to the American College of Medical Genetics guidelines, we identified NDD-CNVs or pathogenic/likely pathogenic CNVs in NDD-linked loci. Gene set analysis was performed to examine the involvement of synaptic dysfunction in EDs. Clinical data were retrospectively examined for ED patients with NDD-CNVs. RESULTS: Of the samples analyzed with aCGH, 70 severe ED patients (98.6%) and 1036 controls (99.1%) passed our quality control filtering. We obtained 189 and 2539 rare CNVs from patients and controls, respectively. NDD-CNVs were identified in 10.0% (7/70) of patients and 2.3% (24/1036) of controls. Statistical analysis revealed a significant association between NDD-CNVs and EDs (odds ratio = 4.69, P = 0.0023). NDD-CNVs in ED patients included 45,X and deletions at KATNAL2, DIP2A, PTPRT, RBFOX1, CNTN4, MACROD2, and FAM92B. Four of these genes were related to synaptic function. In gene set analysis, we observed a nominally significant enrichment of rare exonic CNVs in synaptic signaling in ED patients (odds ratio = 2.55, P = 0.0254). CONCLUSION: Our study provides the first preliminary evidence that NDD-CNVs may confer risk for severe EDs. The pathophysiology may involve synaptic dysfunction.

Treatment-resistant schizophrenia with 22q11.2 deletion and additional genetic defects.

We report a case of a 61-year-old female with 22q11.2 deletion syndrome (22q11.2DS) and a novel heterozygous nonsense variant in MAP1A, identified through whole-genome sequencing (WGS). The patient presented with intellectual developmental disorder, treatment-resistant schizophrenia (SCZ), and multiple congenital anomalies. Despite aggressive pharmacotherapy, she experienced persistent auditory hallucinations and negative symptoms. WGS revealed a 3 Mb deletion at 22q11.2 and a nonsense variant in MAP1A (c.4652T>G, p.Leu1551*). MAP1A, encoding microtubule-associated protein 1A, is crucial for axon and dendrite development and has been implicated in autism spectrum disorder and SCZ. The MAP1A variant may contribute to the severe psychiatric phenotype, as it is thought to influence synaptic plasticity, a process also affected by 22q11.2 deletion. This case highlights the importance of WGS in identifying additional pathogenic variants that may explain phenotypic variability in 22q11.2DS. Thus, WGS can lead to a better understanding of the genetic architecture of 22q11.2DS. However, further studies are needed to elucidate the role of secondary genetic contributors in the diverse clinical presentations of 22q11.2DS.

Assessment of executive functions using a 3D-video game in children and adolescents with ADHD.

Objective: Executive functions are important factors that affect the well-being of children with ADHD. Therefore, inclusion of a convenient assessment of executive dysfunction in diagnosis and treatment of ADHD patients is warranted. However, executive dysfunction assessment presently relies on lab-based neuropsychological tests and symptom rating scales. The present study examined the potential of a 3-D action puzzle video game to reflect ecologically valid executive functioning in pediatric ADHD patients. Methods: Participant gameplay metrics were compared to both their Cambridge Neuropsychological Test Automated Battery (CANTAB) and Conners 3 Parent Form's executive functioning subscale scores. Participants consisted of 33 ADHD and non-ADHD patients aged 8-21. Results: Metrics from gameplay were associated with distinct CANTAB test scores, and a composite score from gameplay was significantly correlated with executive dysfunction from Conners 3. Conclusion: For children with ADHD, cognitive domains related to executive function and overall real-life executive functioning appear to both be measurable via video games. It may be possible to develop individualized behavioral therapy based on the quantitative data obtained from the video game used in this study.

Changes in urinary output due to concomitant administration of sacubitril/valsartan and atrial natriuretic peptide in patients with heart failure: a multicenter retrospective cohort study.

BACKGROUND: Sacubitril/valsartan is an angiotensin receptor neprilysin inhibitor (ARNI) that inhibits the degradation of endogenous natriuretic peptides. Therefore, ARNIs may increase the efficacy of human atrial natriuretic peptide (hANP), a drug for acute heart failure, by mediating its pharmacological mechanism. This study was aimed at evaluating the effects of ARNIs on the pharmacological effects of hANP by using surrogate marker, such as urinary output, in patients with heart failure. METHODS: In this multicenter retrospective cohort study, adult patients with heart failure who were taking angiotensin II receptor blockers (ARB) or ARNIs combined with hANP were enrolled. Information on basic characteristics, clinical laboratory data, medical history, and severity of cardiac insufficiency were collected from electronic medical records. The primary outcome was the change in adjusted fluid balance, calculated by IN-volume (mL/day) - OUT-volume (mL/day) / daily hANP dosage (µg). RESULTS: Ninety-two and 62 patients in the ARB + hANP and ARNI + hANP groups, respectively, were eligible for analysis. The adjusted fluid balance in the ARNI + hANP group was significantly lower than that in the ARB + hANP group (p = 0.001). After propensity score matching, 27 patients from each group were included. Similarly, there was a significant reduction in adjusted fluid balance in the ARNI + hANP group after propensity score matching (p = 0.026). CONCLUSIONS: These findings suggest that ARNIs may enhance the efficacy of hANP and the combination of the two may be effective in the treatment of heart failure.

Analysis of human neuronal cells carrying ASTN2 deletion associated with psychiatric disorders.

Recent genetic studies have found common genomic risk variants among psychiatric disorders, strongly suggesting the overlaps in their molecular and cellular mechanism. Our research group identified the variant in ASTN2 as one of the candidate risk factors across these psychiatric disorders by whole-genome copy number variation analysis. However, the alterations in the human neuronal cells resulting from ASTN2 variants identified in patients remain unknown. To address this, we used patient-derived and genome-edited iPS cells with ASTN2 deletion; cells were further differentiated into neuronal cells. A comprehensive gene expression analysis using genome-edited iPS cells with variants on both alleles revealed that the expression level of ZNF558, a gene specifically expressed in human forebrain neural progenitor cells, was greatly reduced in ASTN2-deleted neuronal cells. Furthermore, the expression of the mitophagy-related gene SPATA18, which is repressed by ZNF558, and mitophagy activity were increased in ASTN2-deleted neuronal cells. These phenotypes were also detected in neuronal cells differentiated from patient-derived iPS cells with heterozygous ASTN2 deletion. Our results suggest that ASTN2 deletion is related to the common pathogenic mechanism of psychiatric disorders by regulating mitophagy via ZNF558.

Study of the genetic association between selected 3q29 region genes and schizophrenia and autism spectrum disorder in the Japanese population.

Psychiatric disorders are highly inheritable, and most psychiatric disorders exhibit genetic overlap. Recent studies associated the 3q29 recurrent deletion with schizophrenia (SCZ) and autism spectrum disorder (ASD). In this study, we investigated the association of genes in the 3q29 region with SCZ and ASD. TM4SF19 and PAK2 were chosen as candidate genes for this study based on evidence from previous research. We sequenced TM4SF19 and PAK2 in 437 SCZ cases, 187 ASD cases and 524 controls in the Japanese population. Through targeted sequencing, we identified 6 missense variants among the cases (ASD & SCZ), 3 missense variants among controls, and 1 variant common to both cases and controls; however, no loss-of-function variants were identified. Fisher's exact test showed a significant association of variants in TM4SF19 among cases (p=0.0160). These results suggest TM4SF19 variants affect the etiology of SCZ and ASD in the Japanese population. Further research examining 3q29 region genes and their association with SCZ and ASD is thus needed.

The needs of patients with noncancer diseases and their families from hospital-based specialized palliative care teams in Japan.

BACKGROUND: Hospital-based specialized palliative care teams (HSPC) are important for symptom management and ethics support, especially during complex decision-making, but the needs of patients with noncancer diseases and their families from the HSPC are unclear. This study aimed to (I) compare the prevalence of symptom between patients with and without cancer and explore changes in symptom intensity after HSPC consultation in patients with noncancer; (II) determine factors related to ethics support; and (III) compare the percentage of request contents from patients and their families when a certified nurse specialist in gerontological nursing (geriatric care nurse below) is present in the HSPC to that when a certified nurse specialist in palliative care (palliative care nurse below) is present in the HSPC. METHODS: We utilized a retrospective cohort study to analyze 761 patients (360 with noncancer and 401 with cancer) referred to our HSPC at the National Center for Geriatrics and Gerontology using 10-year data (since 2011) available in an electronic medical record database. (I) Symptom scores of the Support Team Assessment Schedule were compared between noncancer and cancer groups and between initial and 1-week assessments for noncancer patients. (II) Ethics support was compared between noncancer (including dementia) and cancer. The presence or absence of ethics support requests, which was set as the objective variable, was examined using logistic regression analysis. (III) The percentage of request contents selected from nine items defaulted on the electronic medical record when a geriatric care nurse was present in our HSPC were compared to those when a palliative care nurse was present in our HSPC. RESULTS: Compared to those with cancer, patients with noncancer suffered more from dyspnea and sputum accumulation. More than 10% of patients with noncancer had suffered from pain, dyspnea, sputum accumulation, and anorexia that required treatment, with symptom scores showing improvement after 1 week of HSPC involvement, except for the sputum accumulation. Moreover, for anorexia, symptom scores improved, but >10% of these patients continued to suffer. Patients with noncancer diseases, including dementia, received ethics support than those with cancer without dementia. More requests for ethics support were received when a geriatric care nurse was in the HSPC than when a palliative care nurse was in the HSPC. Logistic regression analysis revealed that requests for ethics support were more frequent from patients or families with impaired decision-making capacity or when the patient lacked an advocate. CONCLUSIONS: The needs of patients with noncancer diseases and families from the HSPC in Japan included (I) symptom management for intractable conditions, such as sputum accumulation; (II) ethics support for patients with noncancer diseases, including dementia, with impaired decision-making capacity, and without advocates; and (III) advice on ethics issues from a geriatric care nurse.

Phenotypes for general behavior, activity, and body temperature in 3q29 deletion model mice.

Whole genome analysis has identified rare copy number variations (CNV) that are strongly involved in the pathogenesis of psychiatric disorders, and 3q29 deletion has been found to have the largest effect size. The 3q29 deletion mice model (3q29-del mice) has been established as a good pathological model for schizophrenia based on phenotypic analysis; however, circadian rhythm and sleep, which are also closely related to neuropsychiatric disorders, have not been investigated. In this study, our aims were to reevaluate the pathogenesis of 3q29-del by recreating model mice and analyzing their behavior and to identify novel new insights into the temporal activity and temperature fluctuations of the mouse model using a recently developed small implantable accelerometer chip, Nano-tag. We generated 3q29-del mice using genome editing technology and reevaluated common behavioral phenotypes. We next implanted Nano-tag in the abdominal cavity of mice for continuous measurements of long-time activity and body temperature. Our model mice exhibited weight loss similar to that of other mice reported previously. A general behavioral battery test in the model mice revealed phenotypes similar to those observed in mouse models of schizophrenia, including increased rearing frequency. Intraperitoneal implantation of Nano-tag, a miniature acceleration sensor, resulted in hypersensitive and rapid increases in the activity and body temperature of 3q29-del mice upon switching to lights-off condition. Similar to the 3q29-del mice reported previously, these mice are a promising model animals for schizophrenia. Successive quantitative analysis may provide results that could help in treating sleep disorders closely associated with neuropsychiatric disorders.

Association between copy number variations in parkin (PRKN) and schizophrenia and autism spectrum disorder: A case-control study.

AIM: The present study aimed to examine the association between copy number variations (CNVs) in parkin (PRKN) and schizophrenia (SCZ) and autism spectrum disorder (ASD) in a large case-control sample. METHOD: Array comparative genomic hybridization was performed on 3111 cases with SCZ, 1236 cases with ASD, and 2713 controls. We systematically prioritized likely pathogenic CNVs (LP-CNVs) in PRKN and examined their association with SCZ and ASD. RESULTS: In total, 3014 SCZ cases (96.9%), 1205 ASD cases (97.5%), and 2671 controls (98.5%) passed quality control. We found that monoallelic carriers of LP-CNVs in PRKN were common (70/6890, 1.02%) and were not at higher risk of SCZ (p = 0.29) or ASD (p = 0.72). We observed that the distribution pattern of LP-CNVs in the Japanese population was consistent with those in other populations. We also identified a patient diagnosed with SCZ and early-onset Parkinson's disease carrying biallelic pathogenic CNVs in PRKN. The absence of Parkinson's symptoms in 10 other monoallelic carriers of the same pathogenic CNV further reflects the lack of effect of monoallelic pathogenic variants in PRKN in the absence of a second hit. CONCLUSION: The present findings suggest that monoallelic CNVs in PRKN do not confer a significant risk for SCZ or ASD. However, further studies to investigate the association between biallelic CNVs in PRKN and SCZ and ASD are warranted.

Exome sequencing of Japanese schizophrenia multiplex families supports the involvement of calcium ion channels.

BACKGROUND: Most sequencing studies of schizophrenia (SCZ) have focused on de novo genetic variants due to interpretability. However, investigating shared rare variants among patients in the same multiplex family is also important. Relatively large-scale analyses of SCZ multiplex families have been done in Caucasian populations, but whether detected variants are also pathogenic in the Japanese population is unclear because of ethnic differences in rare variants. MATERIALS AND METHODS: We performed whole-exome sequencing (WES) of 14 Japanese SCZ multiplex families. After quality control and filtering, we identified rare variants shared among affected persons within the same family. A gene ontology (GO) analysis was performed to identify gene categories possibly affected by these candidate variants. RESULTS: We found 530 variants in 486 genes as potential candidate variants from the 14 SCZ multiplex families examined. The GO analysis demonstrated significant enrichment in calcium channel activity. CONCLUSION: This study provides supporting evidence that calcium ion channel activity is involved in SCZ. WES of multiplex families is a potential means of identifying disease-associated rare variants for SCZ.

Investigation of OLIG2 as a candidate gene for schizophrenia and autism spectrum disorder.

A number of genomic mutations that are thought to be strongly involved in the development of schizophrenia (SCZ) and autism spectrum disorder (ASD) have been identified. Abnormalities involving oligodendrocytes have been reported in SCZ, and as a related gene, oligodendrocyte lineage transcription factor 2 (OLIG2) has been reported to be strongly associated with SCZ. In this study, based on the common disease-rare variant hypothesis, target sequencing of candidate genes was performed to identify rare mutations with a high effect size and the possibility that the identified mutations may increase the risks of SCZ and ASD in the Japanese population. In this study, the exon region of OLIG2 was targeted; 370 patients with SCZ and 192 with ASD were subjected to next-generation sequencing. As a result, one rare missense mutation (A33T) was detected. We used the Sanger method to validate this missense mutation with a low frequency (<1%), and then carried out a genetic association analysis involving 3299 unrelated individuals (1447 with SCZ, 380 with ASD, and 1472 healthy controls) to clarify whether A33T was associated with SCZ or ASD. A33T was not found in either case group, and in only one control. We did not find evidence that p.A33T is involved in the onset of ASD or SCZ; however, associations with this variant need to be evaluated in larger samples to confirm our results.

Exome sequencing analysis of Japanese autism spectrum disorder case-control sample supports an increased burden of synaptic function-related genes.

Autism spectrum disorder (ASD) is a highly heritable, complex disorder in which rare variants contribute significantly to disease risk. Although many genes have been associated with ASD, there have been few genetic studies of ASD in the Japanese population. In whole exomes from a Japanese ASD sample of 309 cases and 299 controls, rare variants were associated with ASD within specific neurodevelopmental gene sets, including highly constrained genes, fragile X mental retardation protein target genes, and genes involved in synaptic function, with the strongest enrichment in trans-synaptic signaling (p = 4.4 × 10-4, Q-value = 0.06). In particular, we strengthen the evidence regarding the role of ABCA13, a synaptic function-related gene, in Japanese ASD. The overall results of this case-control exome study showed that rare variants related to synaptic function are associated with ASD susceptibility in the Japanese population.

Cross-Disorder Analysis of Genic and Regulatory Copy Number Variations in Bipolar Disorder, Schizophrenia, and Autism Spectrum Disorder.

BACKGROUND: We aimed to determine the similarities and differences in the roles of genic and regulatory copy number variations (CNVs) in bipolar disorder (BD), schizophrenia (SCZ), and autism spectrum disorder (ASD). METHODS: Based on high-resolution CNV data from 8708 Japanese samples, we performed to our knowledge the largest cross-disorder analysis of genic and regulatory CNVs in BD, SCZ, and ASD. RESULTS: In genic CNVs, we found an increased burden of smaller (<100 kb) exonic deletions in BD, which contrasted with the highest burden of larger (>500 kb) exonic CNVs in SCZ/ASD. Pathogenic CNVs linked to neurodevelopmental disorders were significantly associated with the risk for each disorder, but BD and SCZ/ASD differed in terms of the effect size (smaller in BD) and subtype distribution of CNVs linked to neurodevelopmental disorders. We identified 3 synaptic genes (DLG2, PCDH15, and ASTN2) as risk factors for BD. Whereas gene set analysis showed that BD-associated pathways were restricted to chromatin biology, SCZ and ASD involved more extensive and similar pathways. Nevertheless, a correlation analysis of gene set results indicated weak but significant pathway similarities between BD and SCZ or ASD (r = 0.25-0.31). In SCZ and ASD, but not BD, CNVs were significantly enriched in enhancers and promoters in brain tissue. CONCLUSIONS: BD and SCZ/ASD differ in terms of CNV burden, characteristics of CNVs linked to neurodevelopmental disorders, and regulatory CNVs. On the other hand, they have shared molecular mechanisms, including chromatin biology. The BD risk genes identified here could provide insight into the pathogenesis of BD.

Rare single-nucleotide DAB1 variants and their contribution to Schizophrenia and autism spectrum disorder susceptibility.

Disabled 1 (DAB1) is an intracellular adaptor protein in the Reelin signaling pathway and plays an essential role in correct neuronal migration and layer formation in the developing brain. DAB1 has been repeatedly reported to be associated with neurodevelopmental disorders including schizophrenia (SCZ) and autism spectrum disorders (ASD) in genetic, animal, and postmortem studies. Recently, increasing attention has been given to rare single-nucleotide variants (SNVs) found by deep sequencing of candidate genes. In this study, we performed exon-targeted resequencing of DAB1 in 370 SCZ and 192 ASD patients using next-generation sequencing technology to identify rare SNVs with a minor allele frequency <1%. We detected two rare missense mutations (G382C, V129I) and then performed a genetic association study in a sample comprising 1763 SCZ, 380 ASD, and 2190 healthy control subjects. Although no statistically significant association with the detected mutations was observed for either SCZ or ASD, G382C was found only in the case group, and in silico analyses and in vitro functional assays suggested that G382C alters the function of the DAB1 protein. The rare variants of DAB1 found in the present study should be studied further to elucidate their potential functional relevance to the pathophysiology of SCZ and ASD.

Child and adolescent psychiatry training curriculum: a global trainee's perspective.

This article is a summary of perspectives on training curricula from child and adolescent psychiatry trainees globally. We aimed to identify the relative strengths, weaknesses and gaps in learning needs from a trainee's perspective. The 20 early-career child psychiatrists who contributed are from 16 countries and represent all the five continents. We could identify some global challenges as well as local/regional challenges that need to be addressed to develop competent child psychiatrists.

Rare genetic variants in the gene encoding histone lysine demethylase 4C (KDM4C) and their contributions to susceptibility to schizophrenia and autism spectrum disorder.

Dysregulation of epigenetic processes involving histone methylation induces neurodevelopmental impairments and has been implicated in schizophrenia (SCZ) and autism spectrum disorder (ASD). Variants in the gene encoding lysine demethylase 4C (KDM4C) have been suggested to confer a risk for such disorders. However, rare genetic variants in KDM4C have not been fully evaluated, and the functional impact of the variants has not been studied using patient-derived cells. In this study, we conducted copy number variant (CNV) analysis in a Japanese sample set (2605 SCZ and 1141 ASD cases, and 2310 controls). We found evidence for significant associations between CNVs in KDM4C and SCZ (p = 0.003) and ASD (p = 0.04). We also observed a significant association between deletions in KDM4C and SCZ (corrected p = 0.04). Next, to explore the contribution of single nucleotide variants in KDM4C, we sequenced the coding exons in a second sample set (370 SCZ and 192 ASD cases) and detected 18 rare missense variants, including p.D160N within the JmjC domain of KDM4C. We, then, performed association analysis for p.D160N in a third sample set (1751 SCZ and 377 ASD cases, and 2276 controls), but did not find a statistical association with these disorders. Immunoblotting analysis using lymphoblastoid cell lines from a case with KDM4C deletion revealed reduced KDM4C protein expression and altered histone methylation patterns. In conclusion, this study strengthens the evidence for associations between KDM4C CNVs and these two disorders and for their potential functional effect on histone methylation patterns.