Research progress of cross-disease miRNA molecular markers in schizophrenia, bipolar disorder and depression / 中华医学遗传学杂志

Micro non-coding RNA (microRNA, miRNA) is a small non-coding RNA involved in gene expression regulation that plays an important role in the onset and development of mental illness. Evidence suggests that several miRNAs are dysregulated in patients with mental illnesses. Because of its stability and quantitative detection in peripheral blood and cerebral fluid, miRNA is a particularly attractive biomarker. The objective of this research is to investigate the relationship between mental illness and miRNAs, as well as the potential processes through which miRNAs contribute to disease etiology. Schizophrenia, bipolar disorder, and depression are three major mental disorders with high disability and mortality. The study explored the particular dysregulated miRNAs for each condition as well as common dysregulated miRNAs across diseases. In this study, which analyzes the findings from relevant studies from 2016 to 2020, the authors discuss the functions of numerous severely dysfunctional miRNAs and their application potential in the field of psychiatry research.

Neurobiology of bipolar disorders: a review of genetic components, signaling pathways, biochemical changes, and neuroimaging findings

Bipolar disorder (BD) is a chronic mental illness characterized by changes in mood that alternate between mania and hypomania or between depression and mixed states, often associated with functional impairment. Although effective pharmacological and non-pharmacological treatments are available, several patients with BD remain symptomatic. The advance in the understanding of the neurobiology underlying BD could help in the identification of new therapeutic targets as well as biomarkers for early detection, prognosis, and response to treatment in BD. In this review, we discuss genetic, epigenetic, molecular, physiological and neuroimaging findings associated with the neurobiology of BD. Despite the advances in the pathophysiological knowledge of BD, the diagnosis and management of the disease are still essentially clinical. Given the complexity of the brain and the close relationship between environmental exposure and brain function, initiatives that incorporate genetic, epigenetic, molecular, physiological, clinical, environmental data, and brain imaging are necessary to produce information that can be translated into prevention and better outcomes for patients with BD.

Exploratory analysis of polygenic risk scores for psychiatric disorders: Applied to dual diagnosis

Background Concurrence of substance use disorders (SUDs) is high in individuals with psychiatric illnesses; more importantly, individuals with both disorders (dual diagnosis) have more severe symptoms. Psychiatric disorders have been proposed to share a genetic susceptibility with SUDs. To explore this shared genetic susceptibility, we analyzed whether any of the polygenic risk scores (PRSs) for psychiatric disorders could be associated to dual diagnosis in patients with schizophrenia (SCZ) or bipolar disorder (BD). Methods We included 192 individuals of Mexican ancestry: 72 with SCZ, 53 with BD, and 67 unrelated controls without psychiatric disorders. We derived calculations of PRS for autism spectrum disorders, attention-deficit/hyperactive disorder, BD, major depression, and SCZ using summary genome-wide association statistics previously published. Results We found that dual diagnosis had a shared genetic susceptibility with major depressive disorder (MDD) and SCZ; furthermore, in individuals with BD, dual diagnosis could be predicted by PRS for MDD. Conclusions Our results reinforce the notion that individuals with dual diagnosis have a higher genetic susceptibility to develop both disorders. However, analyses of larger sample sizes are required to further clarify how to predict risks through PRS within different populations.

Smaller left anterior cingulate cortex in non-bipolar relatives of patients with bipolar disorder

Objective: Bipolar disorder (BD) is highly heritable. The present study aimed at identifying brain morphometric features that could represent markers of BD vulnerability in non-bipolar relatives of bipolar patients. Methods: In the present study, structural magnetic resonance imaging brain scans were acquired from a total of 93 subjects, including 31 patients with BD, 31 non-bipolar relatives of BD patients, and 31 healthy controls. Volumetric measurements of the anterior cingulate cortex (ACC), lateral ventricles, amygdala, and hippocampus were completed using the automated software FreeSurfer. Results: Analysis of covariance (with age, gender, and intracranial volume as covariates) indicated smaller left ACC volumes in unaffected relatives as compared to healthy controls and BD patients (p = 0.004 and p = 0.037, respectively). No additional statistically significant differences were detected for other brain structures. Conclusion: Our findings suggest smaller left ACC volume as a viable biomarker candidate for BD.

The association between social skills deficits and family history of mood disorder in bipolar I disorder

Objective: To compare social skills and related executive functions among bipolar disorder (BD) patients with a family history of mood disorders (FHMD), BD patients with no FHMD and healthy control (HCs). Methods: We evaluated 20 euthymic patients with FHMD, 17 euthymic patients without FHMD, and 31 HCs using the Social Skills Inventory (SSI) and a neuropsychological battery evaluating executive function, inhibitory control, verbal fluency and estimated intelligence. Results: Both BD groups had lower SSI scores than controls. Scores for one subfactor of the social skills questionnaire, conversational skills and social performance, were significantly lower among patients with FHMD than among patients without FHMD (p = 0.019). Both groups of BD patients exhibited significant deficits in initiation/inhibition, but only BD patients with FHMD had deficits in verbal fluency, both compared to HC. There were no associations between social skills questionnaire scores and measures of cognitive function. Conclusion: Euthymic BD patients have lower social skills and executive function performance than HC. The presence of FHMD among BD patients is specifically associated with deficits in conversational and social performance skills, in addition to deficits in verbal fluency. Both characteristics might be associated with a common genetically determined pathophysiological substrate.

Telomere length and hTERT in mania and subsequent remission

Objective: The findings of telomere length (TL) studies in bipolar disorder (BD) are controversial. The aim of the present study was to detect TL, human telomerase reverse transcriptase (hTERT), and brain derived neurotrophic factor (BDNF) in severe mania and subsequent remission. Methods: Twenty-one medication-free male patients and 20 age and gender matched controls were recruited. The patients were followed in the inpatient clinic, and comparisons were made between the same patients in their remission state and controls. Patients received lithium plus antipsychotics during the follow-up period. Quantitative real-time polymerase chain reaction was performed to verify leukocyte TL and whole blood hTERT gene expression levels. Serum BDNF levels were verified by enzyme-linked immunosorbent assay (ELISA). Results: Compared to controls, manic patients presented shorter telomeres (p < 0.001) whose length increased with treatment (p = 0.001). Patients in the late stages showed shorter TL than those in the early stages and controls (p < 0.001). hTERT gene expression levels were up-regulated in mania and remission compared to controls (p = 0.03 and p = 0.01, respectively). BDNF changes did not reach statistically significant levels. Conclusions: TL and hTERT gene expression might reflect a novel aspect of BD pathophysiology and TL might represent a novel biomarker for BD staging.

Déficit atencional con hiperactividad: trastorno multicausal de la conducta, con heredabilidad y comorbilidad genética moderadas / Heritability and genetic comorbidity of attention deficit disorder with hyperactivity

This review aims to summarize information about the genetic etiology of attention deficit disorder with hyperactivity (ADHD), with particular reference to the contributions of our research group. We also discuss the genetic comorbidity estimated from genome-wide single nucleotide polymorphisms (SNP´s) between ADHD and major psychiatric disorders such as schizophrenia (E), major depressive disorder (MDD), bipolar disorder (BD) and autism spectrum disorders (ASD). A high genetic comorbidity was found between E and BD (46%), a moderate comorbidity between MDD and E, MDD and BD and MDD and ADHD (18%, 22% and 10% respectively) and a low comorbidity between E and ASD (2.5%). Furthermore, we show evidence concerning the genetic determination of psychiatric diseases, which is significantly lower when it is estimated from genome-wide SNP´s rather than using traditional quantitative genetic methodology (ADHD = E = 23%, BD = 25%, MDD = 21% and ASD = 17%). From an evolutionary perspective, we suggest that behavioral traits such as hyperactivity, inattention and impulsivity, which play a role in ADHD and perhaps also other hereditary traits which are part of major psychiatric disorders, could have had a high adaptive value during the early stages of the evolution of Homo sapiens. However, they became progressively less adaptive and definitively disadvantageous, to the extreme that they are involved in frequently diagnosed major psychiatric disorders.

Shortened telomere length in bipolar disorder: a comparison of the early and late stages of disease

Objective: Bipolar disorder (BD) has been associated with increased rates of age-related diseases, such as type II diabetes, metabolic syndrome, osteoporosis, and cardiovascular disorders. Several biological findings have been associated with age-related disorders, including increased oxidative stress, inflammation, and telomere shortening. The objective of this study was to compare telomere length among participants with BD at early and late stages and age- and gender-matched healthy controls. Methods: Twenty-six euthymic subjects with BD and 34 healthy controls were recruited. Genomic DNA was extracted from peripheral blood and mean telomere length was measured using real-time quantitative polymerase chain reaction. Results: Telomere length was significantly shorter in both the early and late subgroups of BD subjects when compared to the respective controls (p = 0.002 and p = 0.005, respectively). The sample size prevented additional subgroup analyses, including potential effects of medication, smoking status, and lifestyle. Conclusion: This study is concordant with previous evidence of telomere shortening in BD, in both early and late stages of the disorder, and supports the notion of accelerated aging in BD.

Serum BDNF levels in unaffected first-degree relatives of patients with bipolar disorder

Objective: Unaffected relatives of bipolar disorder (BD) patients have been investigated for the identification of endophenotypes in an attempt to further elucidate the pathophysiology of the disease. Brain-derived neurotrophic factor (BDNF) is considered to be implicated in the pathophysiology of BD, but its role as an endophenotype has been poorly studied. We investigated abnormal serum BDNF levels in BD patients, in their unaffected relatives, and in healthy controls. Methods: BDNF levels were obtained from 25 DSM-IV bipolar I disorder patients, 23 unaffected relatives, and 27 healthy controls. All BD patients were in remission. The unaffected subjects were first-degree relatives of the proband who had no lifetime DSM-IV diagnosis of axis I disorder. BDNF serum levels were determined by sandwich ELISA using monoclonal BDNF-specific antibodies. Results: There were no statistical differences in BDNF levels among BD patients, relatives, and healthy controls. Conclusion: Serum BDNF levels may not indicate high genetic risk for BD, possibly acting as state markers rather than trait markers of the disease.

Severe Darier's disease in a psychiatric patient

Darier’s disease is characterized by dense keratotic lesions in the seborrheic areas of the body such as scalp, forehead, nasolabial folds, trunk and inguinal region. It is a rare genodermatosis, an autosomal dominant inherited disease that may be associated with neuropsichiatric disorders. It is caused by ATPA2 gene mutation, presenting cutaneous and dermatologic expressions. Psychiatric symptoms are depression, suicidal attempts, and bipolar affective disorder. We report a case of Darier’s disease in a 48-year-old female patient presenting severe cutaneous and psychiatric manifestations.

Metabolic syndrome and related variables, insulin resistance, leptin levels, and PPAR-γ2 and leptin gene polymorphisms in a pedigree of subjects with bipolar disorder

Objective: Evidence points to a high prevalence of metabolic dysfunction in bipolar disorder (BD), but few studies have evaluated the relatives of subjects with BD. We conducted a cross-sectional study in an extended family of patients with BD type I. Methods: The available relatives of the same family were interviewed (DSM-IV-R) and assessed in fasting conditions for body mass index, constituent variables of the metabolic syndrome (MS), leptin levels, insulin resistance index, and single nucleotide polymorphisms (SNPs) for the leptin receptor and promoter and PPAR-γ2 genes. The frequency of MS was compared with that recorded in the local general population. Results: Ninety-three relatives of three adults with BD were evaluated (30 aged < 18 years, 63 aged > 18 years). The frequency of MS was similar to that of the general population. Significantly higher frequencies of abnormal glucose, total and low density cholesterol (LDL-c) levels (all p < 0.05), waist circumference (p = 0.057), and leptin and insulin resistance values (in adults only) were observed in the family. Adults with the QQ genotype of the leptin receptor displayed higher LDL-c levels than carriers of the R allele. Conclusions: The associations among BD consanguinity, familial hypercholesterolemia, and leptin receptor SNPs reported herein should be replicated and extended in other pedigrees. .

The Val66Met polymorphism at the BDNF gene does not influence Wisconsin Card Sorting Test results in children and adolescents with bipolar disorder

OBJECTIVES: To assess the role of the Val66Met polymorphism at the brain-derived neurotrophic factor (BDNF) gene on the performance of children and adolescents with bipolar disorder [juvenile bipolar disorder (JBD)] on the Wisconsin Card Sorting Test (WCST). METHODS: Children and adolescents were assessed by the K-SADS-PL and a clinical evaluation for BD and comorbid conditions. Manic and depressive symptoms were assessed with the Young Mania Rating Scale and the Children Depression Rating Scale - Reviewed. The Val66Met polymorphism at the BDNF was genotyped from a blood sample. Patients' IQ and executive functions were assessed by a standard cognitive flexibility test (WCST). RESULTS: Fifty-three subjects were included in the study. No significant difference was observed between the Val/Val and Val/Met+Met/Met groups on any WCST scores in the MANCOVA (F48,5 = .76; p = .59; Perseverative Errors, p = .66; Nonperseverative Errors, p = .58; Categories Completed, p = .34; Attempts to Reach First Category, p=.64; and Percentage of Conceptual Level Responses, p = .99). CONCLUSIONS: Our findings from this sample of children and adolescents with BD do not replicate results from studies of adults and suggest the existence of differences in the neurobiology of this disorder across the life cycle. Investigations of larger samples are necessary to confirm these data.

Rol del sistema de genes CLOCK en las alteraciones del ritmo circadiano en pacientes con Trastorno Bipolar. Estudio de asociación genómica amplia / Role of CLOCK Genes in Circadian Rhythm Alterations, in Patients with Bipolar Disorder. Genome-wide Association Study

Introducción: Las anomalías del ritmo circadiano en el transcurso del TB ha motivado la búsqueda de anomalías en los genes CLOCK asociados a la génesis de ritmos circadianos que podrían estar involucrados en este aspecto de la compleja patología del TB. A pesar de ingentes búsquedas, no se han registrado hallazgos significativos en estudios de asociación amplia de genoma (GWAS/genome-wide association studies). Hay por lo menos 3 razones para explicar estos resultados negativos. En primer lugar el hecho de que los rasgos genéticos de patologías complejas, como es el caso del TB, son habitualmente poligénicos. En segundo término, la organización del reloj/es circadiano/s es bastante más compleja de lo que habitualmente se está dispuesto a admitir; y en tercer lugar, el riesgo genético para TB podría ser compartido entre varias patologías diferentes. Objetivos. Investigar la posibilidad de una asociación entre anomalías en las agrupaciones genéticas responsables de la generación de ritmos circadianos y TB, para lo cual se analizaron las redes constitutivas de los genes CLOCK en por lo menos tres niveles: 1) los genes CLOCK centrales, 2) los genes moduladores de genes CLOCK centrales y 3) los genes controlados por los genes CLOCK centrales. Método: Mediante el uso de método de asociación amplia de genoma con umbrales permisivos se intentó establecer asociaciones significativas entre genes CLOCK y TB comparados con genes control, ademas de incluir asociaciones significativas entre genes CLOCK y TB comparados con genes control, además de incluir asociaciones con otras enfermedades que comparten rasgos clínicos y/o genéticos con el TB, como la Depresión Mayor (DM), Esquizofrenia (E), Trastorno por Déficit de Atención e Hiperactividad (TDAH). Luego de establecer estas asociaciones se compararon los resultados con un conjunto de genes sensibles al litio (Li) y otro grupo sensible a valproato (VPO). Las asociaciones entre TEB y respuesta al litio y/o valproato ...

Introduction. Circadian rythm abnormalities during bipolar disoder has prompetd the search for alterations in CLOCK genes responible for generating circadian rythms, which could be envolved with this complex issue of biipolar disorder. In spite of urgent search, no sinificative results ave been reached in genome wide association scales studies (GWAS). At least three rehaznos could account for this fact: first, genetic traits of complex pathology are usually poligenic, second circadian clock organization is far more complex than usually admitted, and third bipolar disorder genetic risk could be shared with other different diseases. Goals. Search for the possibiity of an association between genetic assemblies anormalies responsible for circadian clock rhythm generation and bipolar disorder. Whith that objective, CLOCK genes networks were analyzed n at least three levels: 1) central CLOCK genes, 2) central CLOCK genes modulators and 3) central CLOCK controlled genes. Method. Using GWAS with permissive tresholds and control comparison, a significative association between CLOCK genes and bipolar disorder was searched, including involvement with other diseases that share common (ADHD). After establishing these associations, results were compared for Lithium and valproate sensitive genes associations. Associations between bipolar disorder, CLOCK genes, lithium and valproate sensitive genes were enriched through comparisons with rhythmic, weakly rhythmic and arrhythmic genes. Results. Significative enrichments were found between CLOCK central genes, bipolar disorder and lithium and valproate sensitive genes, not incluiding CLOCK genes modulators. Associations between bipolar disorder, lithium and valproate sensitive genes and rhythmic genes also were significative, excluding weakly rhythmic and arrhythmic genes. GWAS analysis with flexible tresholds made possible the regognition of association between central CLOCK genes and bipolar disorder, identifying candidate ..

La etiología de la esquizofrenia / The etiology of schizophrenia

Las investigaciones realizadas en los últimos años iniciaron una nueva era de conocimiento de los factores de riesgo de la esquizofrenia. Por otra parte, los métodos de estudio del genoma completo han revolucionado el campo del mapeado genético de la esquizofrenia. Estudios genéticos recientes sugieren que la variación genética rara y la variación genética común tienen una función importante en la arquitectura genética de la esquizofrenia, que el modelo poligénico es correcto, e indican una superposición de los factores genéticos que confieren susceptibilidad a la esquizofrenia y otros trastornos psiquiátricos, como el trastorno bipolar y el autismo (pleotropía). Los programas de resecuenciación del genoma completo permitirán una disección más profunda de la genética molecular de la enfermedad. Uno de los desafíos importantes de la psiquiatría genética es la traducción de las asociaciones estadísticas detectadas en estudios de genoma completo en una mejor comprensión fisiopatológica de la esquizofrenia.

Research conducted in recent years represents a new dawn of knowledge for the risk factors of schizophrenia, and genome-wide approaches have revolutionized the field of genetic mapping of schizophrenia. The aggregate genetic data increasingly support a combination of rare and common genetic variation in schizophrenia, a major role for polygenic inheritance, and a genetic overlap (pleiotropy) of schizophrenia and other psychiatric disorders, such as bipolar disorder and autism. A main challenge for the field is the translation of established genetic associations into a better pathophysiological understanding of schizophrenia. The current and upcoming resequencing programs - both exomes (all exons) and full genomes - and genome-wide transcriptional analyses will allow a more thorough dissection of the molecular genetics of the disorder.

Associação entre polimorfismos genéticos e transtorno bipolar / Associations between genetic polymorphisms and bipolar disorder

Transtorno bipolar (TB) é uma doença comum que afeta aproximadamente 1% da população. Apresenta características crônicas e agudas graves, com índices de remissão de baixa e alta prevalência de comorbidades clínicas e psiquiátricas. O objetivo do presente artigo é sintetizar dados de vários artigos que investigaram polimorfismos genéticos associados com TB. Dentre os 129 artigos selecionados, identificaram-se 79 (85,87%) genes associados com TB. Essa análise identificou cinco genes que são os mais citados na literatura: CANAC1C, DAOA, TPH2, ANK3 e DISC1. Dos 92 genes identificados nesses artigos, 33 (35,87%) não mostraram associação com TB. Essa análise mostrou que, apesar dos avanços recentes com relação ao papel do polimorfismo genético na predisposição para TB, mais pesquisas ainda são necessárias para elucidar sua influência sobre esse transtorno.

Bipolar disorder (BD) is a common disorder that affects approximately 1% of the population. It is associated with both chronic and acute severe features, such as low remission rates and a high prevalence of clinical and psychiatric comorbidities. The aim of the present article is to synthesize data from various articles that investigated genetic polymorphisms associated with BD. The 129 articles selected identified 79 (85.87%) genes associated with BD. This analysis identified the five genes that are the most cited in the literature: CANAC1C, DAOA, TPH2, ANK3 and DISC1. Of the 92 genes identified in these articles, 33 (35.87%) showed no association with BD. This analysis showed that, despite recent advances with respect to the role of genetic polymorphism in predisposition to BD, further research is still required to elucidate its influence on this disorder.

Genetic association of the EGR2 gene with bipolar disorder in Korea

The early growth response gene 2 (EGR2) is located at chromosome 10q21, one of the susceptibility loci in bipolar disorder (BD). EGR2 is involved in cognitive function, myelination, and signal transduction related to neuregulin-ErbB receptor, Bcl-2 family proteins, and brain-derived neurotrophic factor. This study investigated the genetic association of the EGR2 gene with BD and schizophrenia (SPR) in Korea. In 946 subjects (350 healthy controls, 352 patients with BD, and 244 with SPR), nine single nucleotide polymorphisms (SNPs) in the EGR2 gene region were genotyped. Five SNPs showed nominally significant allelic associations with BD (rs2295814, rs61865882, rs10995315, rs2297488, and rs2297489), and the positive associations of all except rs2297488 remained significant after multiple testing correction. Linkage disequilibrium structure analysis revealed two haplotype blocks. Among the common identified haplotypes (frequency > 5%), 'T-G-A-C-T (block 1)' and 'A-A-G-C (block 2)' haplotypes were over-represented, while 'C-G-G-T-T (block 1)' haplotype was under-represented in BD. In contrast, no significant associations were found with SPR. Although an extended analysis with a larger sample size or independent replication is required, these findings suggest a genetic association of EGR2 with BD. Combined with a plausible biological function of EGR2, the EGR2 gene is a possible susceptibility gene in BD.