Association study of a monoamine oxidase a gene promoter polymorphism with major depressive disorder and antidepressant response

Omics approaches open new horizons in major depressive disorder: from biomarkers to precision medicine

Major depressive disorder (MDD) is a recurrent episodic mood disorder that represents the third leading cause of disability worldwide. In MDD, several factors can simultaneously contribute to its development, which complicates its diagnosis. According to practical guidelines, antidepressants are the first-line treatment for moderate to severe major depressive episodes. Traditional treatment strategies often follow a one-size-fits-all approach, resulting in suboptimal outcomes for many patients who fail to experience a response or recovery and develop the so-called "therapy-resistant depression". The high biological and clinical inter-variability within patients and the lack of robust biomarkers hinder the finding of specific therapeutic targets, contributing to the high treatment failure rates. In this frame, precision medicine, a paradigm that tailors medical interventions to individual characteristics, would help allocate the most adequate and effective treatment for each patient while minimizing its side effects. In particular, multi-omic studies may unveil the intricate interplays between genetic predispositions and exposure to environmental factors through the study of epigenomics, transcriptomics, proteomics, metabolomics, gut microbiomics, and immunomics. The integration of the flow of multi-omic information into molecular pathways may produce better outcomes than the current psychopharmacological approach, which targets singular molecular factors mainly related to the monoamine systems, disregarding the complex network of our organism. The concept of system biomedicine involves the integration and analysis of enormous datasets generated with different technologies, creating a "patient fingerprint", which defines the underlying biological mechanisms of every patient. This review, centered on precision medicine, explores the integration of multi-omic approaches as clinical tools for prediction in MDD at a single-patient level. It investigates how combining the existing technologies used for diagnostic, stratification, prognostic, and treatment-response biomarkers discovery with artificial intelligence can improve the assessment and treatment of MDD.

Machine learning accelerates pharmacophore-based virtual screening of MAO inhibitors

Nowadays, an efficient and robust virtual screening procedure is crucial in the drug discovery process, especially when performed on large and chemically diverse databases. Virtual screening methods, like molecular docking and classic QSAR models, are limited in their ability to handle vast numbers of compounds and to learn from scarce data, respectively. In this study, we introduce a universal methodology that uses a machine learning-based approach to predict docking scores without the need for time-consuming molecular docking procedures. The developed protocol yielded 1000 times faster binding energy predictions than classical docking-based screening. The proposed predictive model learns from docking results, allowing users to choose their preferred docking software without relying on insufficient and incoherent experimental activity data. The methodology described employs multiple types of molecular fingerprints and descriptors to construct an ensemble model that further reduces prediction errors and is capable of delivering highly precise docking score values for monoamine oxidase ligands, enabling faster identification of promising compounds. An extensive pharmacophore-constrained screening of the ZINC database resulted in a selection of 24 compounds that were synthesized and evaluated for their biological activity. A preliminary screen discovered weak inhibitors of MAO-A with a percentage efficiency index close to a known drug at the lowest tested concentration. The approach presented here can be successfully applied to other biological targets as target-specific knowledge is not incorporated at the screening phase.

Genetic Landscape of Major Depressive Disorder: Assessment of Potential Diagnostic and Antidepressant Response Markers

BACKGROUND

The clinical heterogeneity in major depressive disorder (MDD), variable treatment response, and conflicting findings limit the ability of genomics toward the discovery of evidence-based diagnosis and treatment regimen. This study attempts to curate all genetic association findings to evaluate potential variants for clinical translation.

METHODS

We systematically reviewed all candidates and genome-wide association studies for both MDD susceptibility and antidepressant response, independently, using MEDLINE, particularly to identify replicated findings. These variants were evaluated for functional consequences using different in silico tools and further estimated their diagnostic predictability by calculating positive predictive values.

RESULTS

A total of 217 significantly associated studies comprising 1200 variants across 545 genes and 128 studies including 921 variants across 412 genes were included with MDD susceptibility and antidepressant response, respectively. Although the majority of associations were confirmed by a single study, we identified 31 and 18 replicated variants (in at least 2 studies) for MDD and antidepressant response. Functional annotation of these 31 variants predicted 20% coding variants as deleterious/damaging and 80.6% variants with regulatory effect. Similarly, the response-related 18 variants revealed 25% coding variant as damaging and 88.2% with substantial regulatory potential. Finally, we could calculate the diagnostic predictability of 19 and 5 variants whose positive predictive values ranges from 0.49 to 0.66 for MDD and 0.36 to 0.66 for response.

CONCLUSIONS

The replicated variants presented in our data are promising for disease diagnosis and improved response outcomes. Although these quantitative assessment measures are solely directive of available observational evidence, robust homogenous validation studies are required to strengthen these variants for molecular diagnostic application.

Effect of MAOA DNA Methylation on Human in Vivo Protein Expression Measured by [11C]harmine Positron Emission Tomography

BACKGROUND

Epigenetic modifications like DNA methylation are understood as an intermediary between environmental factors and neurobiology. Cerebral monoamine oxidase A (MAO-A) levels are altered in depression, as are DNA methylation levels within the MAOA gene, particularly in the promoter/exon I/intron I region. An effect of MAOA methylation on peripheral protein expression was shown, but the extent to which methylation affects brain MAO-A levels is not fully understood.

METHODS

Here, the influence of MAOA promoter/exon I/intron I region DNA methylation on global MAO-A distribution volume (VT), an index of MAO-A density, was assessed via [11C]harmine positron emission tomography in 22 patients (14 females) suffering from seasonal affective disorder and 30 healthy controls (17 females).

RESULTS

No significant influence of MAOA DNA methylation on global MAO-A VT was found, despite correction for health status, sex, season, and MAOA variable number of tandem repeat genotype. However, season affected average methylation in women, with higher levels in spring and summer (Puncorr = .03). We thus did not find evidence for an effect of MAOA DNA methylation on brain MAO-A VT.

CONCLUSIONS

In contrast to a previous study demonstrating an effect of methylation of a MAOA promoter region located further 5' on brain MAO-A, MAOA methylation of the region assessed here appears to affect brain protein levels to a limited extent at most. The observed effect of season on methylation levels is in accordance with extensive evidence for seasonal effects within the serotonergic system.

CLINICALTRIALS.GOV IDENTIFIER

NCT02582398 (https://clinicaltrials.gov/ct2/show/NCT02582398).

The MAOA rs979605 Genetic Polymorphism Is Differentially Associated with Clinical Improvement Following Antidepressant Treatment between Male and Female Depressed Patients

Major depressive disorder (MDD) is the leading cause of disability worldwide. Treatment with antidepressant drugs (ATD), which target monoamine neurotransmitters including serotonin (5HT), are only modestly effective. Monoamine oxidase (MAO) metabolizes 5HT to 5-hydroxy indoleacetic acid (5HIAA). Genetic variants in the X-chromosome-linked MAO-encoding genes, MAOA and MAOB, have been associated with clinical improvement following ATD treatment in depressed patients. Our aim was to analyze the association of MAOA and MAOB genetic variants with (1) clinical improvement and (2) the plasma 5HIAA/5HT ratio in 6-month ATD-treated depressed individuals. Clinical (n = 378) and metabolite (n = 148) data were obtained at baseline and up to 6 months after beginning ATD treatment (M6) in patients of METADAP. Mixed-effects models were used to assess the association of variants with the Hamilton Depression Rating Scale (HDRS) score, response and remission rates, and the plasma 5HIAA/5HT ratio. Variant × sex interactions and dominance terms were included to control for X-chromosome-linked factors. The MAOA rs979605 and MAOB rs1799836 polymorphisms were analyzed. The sex × rs979605 interaction was significantly associated with the HDRS score (p = 0.012). At M6, A allele-carrying males had a lower HDRS score (n = 24, 10.9 ± 1.61) compared to AA homozygous females (n = 14, 18.1 ± 1.87; p = 0.0067). The rs1799836 polymorphism was significantly associated with the plasma 5HIAA/5HT ratio (p = 0.018). Overall, CC/C females/males had a lower ratio (n = 44, 2.18 ± 0.28) compared to TT/T females/males (n = 60, 2.79 ± 0.27; p = 0.047). The MAOA rs979605 polymorphism, associated with the HDRS score in a sex-dependent manner, could be a useful biomarker for the response to ATD treatment.

MAOA uVNTR Genetic Variant and Major Depressive Disorder: A Systematic Review

Major Depressive Disorder (MDD) is a highly prevalent multifactorial psychopathology affected by neurotransmitter levels. Monoamine Oxidase A (MAOA) influences several neural pathways by modulating these levels. This systematic review (per PRISMA protocol and PECOS strategy) endeavors to understand the MAOA uVNTR polymorphism influence on MDD and evaluate its 3R/3R and 3R* genotypic frequencies fluctuation in MDD patients from different populations. We searched the Web of Science, PubMed, Virtual Health Library, and EMBASE databases for eligible original articles that brought data on genotypic frequencies related to the MAOA uVNTR variant in patients with MDD. We excluded studies with incomplete data (including statistical data), reviews, meta-analyses, and abstracts. Initially, we found 43 articles. After removing duplicates and applying the inclusion/exclusion criteria, seven articles remained. The population samples studied were predominantly Asians, with high 3R and 4R allele frequencies. Notably, we observed higher 3R/3R (female) and 3R* (male) genotype frequencies in the healthy control groups and higher 4R/4R (female) and 4R* (male) genotype frequencies in the MDD groups in the majority of different populations. Despite some similarities in the articles analyzed, there is still no consensus on the MAOA uVNTR variant’s role in MDD pathogenesis.

Chronic cortisol differentially impacts stem cell-derived astrocytes from major depressive disorder patients

Major depressive disorder (MDD) is a prevalent psychiatric disorder, and exposure to stress is a robust risk factor for MDD. Clinical data and rodent models have indicated the negative impact of chronic exposure to stress-induced hormones like cortisol on brain volume, memory, and cell metabolism. However, the cellular and transcriptomic changes that occur in the brain after prolonged exposure to cortisol are less understood. Furthermore, the astrocyte-specific contribution to cortisol-induced neuropathology remains understudied. Here, we have developed an in vitro model of "chronic stress" using human induced pluripotent stem cell (iPSC)-derived astrocytes treated with cortisol for 7 days. Whole transcriptome sequencing reveals differentially expressed genes (DEGs) uniquely regulated in chronic cortisol compared to acute cortisol treatment. Utilizing this paradigm, we examined the stress response transcriptome of astrocytes generated from MDD patient iPSCs. The MDD-specific DEGs are related to GPCR ligand binding, synaptic signaling, and ion homeostasis. Together, these data highlight the unique role astrocytes play in the central nervous system and present interesting genes for future study into the relationship between chronic stress and MDD.

Genetic Biomarkers in Association with Depressive Disorder in UAE Residents: A Pilot Case Study

Objectives

We sought to explore the expression of genes associated with depressive disorder in patients with depression compared to control patients. A large body of research in the area of genetics has shown familial aggregation for depressive disorders. The purpose of this study was to identify genetic risk factors in developing depression, particularly among the population residing in the UAE.

Methods

We investigated five associated genes (PPARGC1A, CAMKMT, HSD11B1, SLC6A4, and MAOA) previously linked to depression and anxiety in other populations. The study was carried out in Al Ain, although participants were from different nationalities. Blood samples were collected over a period of seven months, and lab work was carried out over a period of two months from September 1, 2018 to May 30, 2019. We screened the prevalence of the PPARGC1A, CAMKMT, HSD11B1, SLC6A4, and MAOA in 29 patients with depressive disorder and 30 controls using the quantitative real-time polymerase chain reaction method.

Results

The expression of the PPARGC1A gene, studied for the first time in the UAE population. The independent t-test was used to check the significance of difference between the expression levels of target genes where the control was set at a reference level of 1.0. PPARGC1A gene is lower among the depressed group which showed mean difference: 0.4 and p-value: 0.02, indicating a strong association with depression. No significant difference was found in the genes' expression of CAMKMT with p-value 0.150, MAOA p-value 0.070, SLC6A4 p-value 0.750, and HSD11B1 p-value 0.100 in two groups in comparison with (p < 0.050).

Conclusions

These results open several possibilities for further research to study the role of this gene as a protective factor against developing depression.

Molecular Targets of Cannabinoids Associated with Depression

Novel therapeutic strategies are needed to address depression, a major neurological disorder affecting hundreds of millions of people worldwide. Cannabinoids and their synthetic derivatives have demonstrated numerous neurological activities and may potentially be developed into new treatments for depression. This review highlights cannabinoid (CB) receptors, monoamine oxidase (MAO), N-methyl-D-aspartate (NMDA) receptor, gamma-aminobutyric acid (GABA) receptor, and cholecystokinin (CCK) receptor as key molecular targets of cannabinoids that are associated with depression. The anti-depressant activity of cannabinoids and their binding modes with cannabinoid receptors are discussed, providing insights into rational design and discovery of new cannabinoids or cannabimimetic agents with improved druggable properties.

The role of monoamine oxidase enzymes in the pathophysiology of neurological disorders

Monoamine oxidase enzymes are responsible for the degredation of serotonin, dopamine, and norepinephrine in the central neurvous system. Although it has been nearly 100 years since they were first described, we are still learning about their role in the healthy brain and how they are altered in various disease states. The present review provides a survey of our current understanding of monoamine oxidases, with a focus on their contributions to neuropsychiatric, neurodevelopmental, and neurodegenerative disease. Important species differences in monoamine oxidase function and development in the brain are highlighted. Sex-specific monoamine oxidase regulatory mechanisms and their implications for various neurological disorders are also discussed. While our understanding of these critical enzymes has expanded over the last century, gaps exist in our understanding of sex and species differences and the roles monoamine oxidases may play in conditions often comorbid with neurological disorders.

Pharmacogenetic association of bi- and triallelic polymorphisms of SLC6A4 with antidepressant response in major depressive disorder

BACKGROUND

Antidepressants (ADs) are the main clinical therapy for depression, but approximately half of users do not get adequate response. The biallelic (5-HTTLPR) and triallelic (5-HTTLPR/rs25531) polymorphisms in SLC6A4 have been frequently investigated, but their associations with ADs response are in controversy. Here, we performed a meta-analysis to assess their modulation effect to ADs response in major depressive disorder (MDD).

METHODS

We performed literature search in PubMed, Web of Science and EMBASE before June 2019. Pooled analysis of genetic associations with response and remission, meta-regression and sensitivity analysis were performed, and publication bias was assessed.

RESULTS

Literature search yielded 49 eligible studies with 46 and 10 studies for biallelic and triallelic polymorphism, respectively. L allele of 5-HTTLPR was associated with both of response and remission rates. In the Caucasians using SSRIs only, carriers of LL/LS or LL genotype were more likely to be responders compared to SS carriers (LL/LS vs. SS: OR=1.55, 95%CI 1.20-2.00, p=0.001; LL vs. SS: OR=1.97, 95%CI 1.45-2.67, p<0.001). Similar associations were also found with remission rate. However, no effects on response or remission were found in the Asians or mixed/other antidepressant subgroups. Additionally, the 5-HTTLPR/rs25531 triallelic polymorphism may not associate with ADs response. Meta-regression showed that percent of female in participants, year of publication and treatment duration modulated the association in Caucasians.

CONCLUSION

5-HTTLPR, instead of 5-HTTLPR/rs25531 triallelic polymorphism, may exert as a marker for the prediction of response to SSRIs in Caucasians with MDD.

Mitochondrial-Targeted and Near-Infrared Fluorescence Probe for Bioimaging and Evaluating Monoamine Oxidase A Activity in Hepatic Fibrosis

Monoamine oxidase A (MAO-A) is a promising diagnostic marker for cancer, depression, Parkinson's disease, and liver disease. The fluorescence detection of MAO-A in living animals is of extreme importance for the early diagnosis of related diseases. However, the development of specific and mitochondrial-targeted and near-infrared (NIR) fluorescence MAO-A probes is still inadequate. Here, we designed and synthesized four NIR fluorescence probes containing a dihydroxanthene (DH) skeleton to detect MAO-A in complex biological systems. The specificity of our representative probe DHMP2 displays a 31-fold fluorescence turn-on in vitro, and it can effectively accumulate in the mitochondria and specifically detect the endogenous MAO-A concentrations in PC-3 and SH-SY5Y cell lines. Furthermore, the probe DHMP2 can be used to visualize the endogenous MAO-A activity in zebrafish and tumor-bearing mice. More importantly, it is the first time that the MAO-A activity of hepatic fibrosis tissues is detected through the probe DHMP2. The present study shows that the synthesized DHMP2 might serve as a potential tool for monitoring MAO-A activity in vivo and diagnosing related diseases.

The relationships among MAOA, COMT Val158Met, and 5-HTTLPR polymorphisms, newborn stress reactivity, and infant temperament

INTRODUCTION

Variance in hypothalamic-pituitary-adrenal (HPA) axis reactivity is considered to be one of the sources of differences in infant temperament. The cortisol enters into interactions with dopamine and serotonin, so it is expected that polymorphisms in genes coding monoamine metabolism influence both HPA axis reactivity and temperament.

METHODS

We therefore explore the relationship among 5-HTTLPR S/L, MAOA H/L, and COMT Val158Met polymorphisms, the stress reaction of newborn infants after a heel stick blood draw (measured by determining salivary cortisol at three time points), and temperament assessed at the age of 3 months using Rothbart's Infant Behavior Questionnaire-Revised (IBQ-R) with a sample of 84 infants.

RESULTS

The decrease in the salivary cortisol correlated with nine primary scales and all three secondary scales of IBQ-R. Children with a greater cortisol decrease were assessed as less susceptible to negative emotions, more extraverted, and more regulated. The polymorphisms that were observed were related both to the course of the stress reaction and to temperament. The 5-HTTLPR S allele was connected to higher scores for Negative Emotionality and lower scores for Orienting/Regulatory Capacity. The presence of the MAOA L allele predisposed its carriers to higher scores for Negative Emotionality, lower scores for Orienting/Regulatory Capacity, and a lower decrease in cortisol. The Met allele of COMT Val158Met polymorphism was connected to a higher Positive Affectivity/Surgency and Orienting/Regulatory Capacity and a greater cortisol decrease.

CONCLUSIONS

Contrary to previous studies referring mainly basal cortisol and its increase, the results of our study emphasize the importance of cortisol elimination in infant temperament. Another interesting finding was a higher cortisol increase, higher Distress to Limitations, Negative Emotionality, and Approach in MAOA LL homozygotes which are traditionally understood as more vulnerable toward early stress in developing later externalizing behavior.

The cellular and molecular basis of major depressive disorder: towards a unified model for understanding clinical depression

Major depressive disorder (MDD) is considered a serious public health issue that adversely impacts an individual's quality of life and contributes significantly to the global burden of disease. The clinical heterogeneity that exists among patients limits the ability of MDD to be accurately diagnosed and currently, a symptom-based approach is utilized in many cases. Due to the complex nature of this disorder, and lack of precise knowledge regarding the pathophysiology, effective management is challenging. The aetiology and pathophysiology of MDD remain largely unknown given the complex genetic and environmental interactions that are involved. Nonetheless, the aetiology and pathophysiology of MDD have been the subject of extensive research, and there is a vast body of literature that exists. Here we overview the key hypotheses that have been proposed for the neurobiology of MDD and highlight the need for a unified model, as many of these pathways are integrated. Key pathways discussed include neurotransmission, neuroinflammation, clock gene machinery pathways, oxidative stress, role of neurotrophins, stress response pathways, the endocannabinoid and endovanilloid systems, and the endogenous opioid system. We also describe the current management of MDD, and emerging novel therapies, with particular focus on patients with treatment-resistant depression (TRD).

Serotonin Transporter Binding Potentials in Brain of Juvenile Monkeys 1 Year After Discontinuation of a 2-Year Treatment With Fluoxetine

BACKGROUND

The potential long-term effects of childhood fluoxetine therapy on brain serotonin systems were studied using a nonhuman primate model, the rhesus monkey.

METHODS

Juvenile male rhesus (1-4 years of age, corresponding to 4-11 years of age in children) were treated orally with fluoxetine (2 mg/kg) or vehicle daily for 2 years and removed from treatment during the third year. Each treatment group was assigned an equal number of subjects with low and high transcription polymorphisms of MAOA. One year after discontinuation of treatment, positron emission tomography scans were conducted (n = 8 treated monkeys, n = 8 control monkeys) using [¹¹C]DASB to quantify serotonin transporter in 16 cortical and subcortical regions.

RESULTS

Fluoxetine-treated monkeys with MAOA low transcription polymorphism had significantly lower [¹¹C]DASB binding potentials than control monkeys. This finding was seen throughout the brain but was strongest in prefrontal and cingulate cortices. The MAOA × fluoxetine interaction was enhanced by binding potentials that were nonsignificantly higher in monkeys with high transcription polymorphism.

CONCLUSIONS

Juvenile fluoxetine treatment has residual posttreatment effects on brain serotonin transporter that depend on MAOA genotype. MAOA genotype may be important to consider when treating children with fluoxetine.

Imputation of behavioral candidate gene repeat variants in 486,551 publicly-available UK Biobank individuals

Some of the most widely studied variants in psychiatric genetics include variable number tandem repeat variants (VNTRs) in SLC6A3, DRD4, SLC6A4, and MAOA. While initial findings suggested large effects, their importance with respect to psychiatric phenotypes is the subject of much debate with broadly conflicting results. Despite broad interest, these loci remain absent from the largest available samples, such as the UK Biobank, limiting researchers' ability to test these contentious hypotheses rigorously in large samples. Here, using two independent reference datasets, we report out-of-sample imputation accuracy estimates of >0.96 for all four VNTR variants and one modifying SNP, depending on the reference and target dataset. We describe the imputation procedures of these candidate variants in 486,551 UK Biobank individuals, and have made the imputed variant data available to UK Biobank researchers. This resource, provided to the scientific community, will allow the most rigorous tests to-date of the roles of these variants in behavioral and psychiatric phenotypes.

Psychopathological consequences of maltreatment among children and adolescents: A systematic review of the GxE literature

BACKGROUND

In the last years, several studies focused on the role of Gene-Environment interactions (GxE) in influencing psychopathological outcomes among maltreated children and adolescents. These studies analysed the effect of different genetic variations.

AIMS

The aim of the present review is to provide an overview of studies investigating GxE effects among maltreated children and adolescents.

METHODS AND PROCEDURES

A systematic literature review was performed by using the following keywords: "Child maltreatment" and "GxE", "Child maltreatment" and "Psychopathology", "Gene-Environment interaction", "Gene-environment correlation", "GxE and psychopathology", "Childhood trauma" and "Psychiatric symptoms", "Early adverse life events", "Early life stress", "Antisocial behaviour", "Depression", "Internalizing symptoms", through the following electronic databases: PubMed, Scopus and PsycINFO, from 2006 to 2017, finding a total of 31 papers.

OUTCOMES AND RESULTS

The present review confirm that maltreatment produces worse psychopathological outcomes (antisocial behaviour, depression, and other psychiatric traits) in subjects with a specific genetic vulnerability.

CONCLUSIONS AND IMPLICATIONS

Comprehending the pathways from child maltreatment to psychopathology in their full complexity will be essential to build efficacious preventive and therapeutic protocols.

MAOA-VNTR Genotype Effects on Ventral Striatum-Hippocampus Network in Alzheimer's Disease: Analysis Using Structural Covariance Network and Correlation with Neurobehavior Performance

Functional polymorphisms in the promoter region of the monoamine oxidase A (MAOA) gene are associated with brain MAOA activity and transcriptional efficiency in patients with Alzheimer's disease (AD). This study investigated structural covariance networks mediated by MAOA-variable number tandem repeat (VNTR) genotypes in patients with AD, and assessed whether this effect was associated with sex. A total of 193 patients with AD were classified into four genotype groups based on MAOA transcriptional efficiency (female low [L], low-high + high activity groups [LH + H]; male L, male H groups). Structural covariance networks were constructed focusing on triple-network and striatal networks. Covariance strength was analyzed in the four groups, and the genotype and sex main effects and their interactions were analyzed. Significant peak cluster volumes were correlated with neurobehavioral scores to establish the clinical significance. MAOA genotypes mediated the structural covariance strength on the dorsolateral prefrontal cortex (dLPFC)-caudate axis in both sexes, but a higher covariance strength was shown in the female L group and male H group. The independent effect of male sex was related to higher covariance strength in the frontal medial superior region in the dLPFC, dorsal caudate (DC), and ventral superior striatum (VSs) seeds. In contrast, female sex had higher covariance strength in the frontal opercular areas anchored by the dLPFC, DC, and VSs seeds. Topographies showing higher covariance strength with sex interactions were found in the male H group and female L group in the dLPFC supplementary motor axis, DC-SMA, and DC-precentral axis. In our patients with AD, MAOA-VNTR polymorphisms and sex had independent and interactive effects on structural covariance networks, of which the dLPFC-, VSs-, and DC-anchored networks represented major endophenotypes that determined cognitive outcomes. The sex-genotype interaction model suggested that male high activity and female low activity may modulate brain morphometric connectivity and determine cognitive scores.

Genetic variants in major depressive disorder: From pathophysiology to therapy

In spite of promising preclinical results there is a decreasing number of new registered medications in major depression. The main reason behind this fact is the lack of confirmation in clinical studies for the assumed, and in animals confirmed, therapeutic results. This suggests low predictive value of animal studies for central nervous system disorders. One solution for identifying new possible targets is the application of genetics and genomics, which may pinpoint new targets based on the effect of genetic variants in humans. The present review summarizes such research focusing on depression and its therapy. The inconsistency between most genetic studies in depression suggests, first of all, a significant role of environmental stress. Furthermore, effect of individual genes and polymorphisms is weak, therefore gene x gene interactions or complete biochemical pathways should be analyzed. Even genes encoding target proteins of currently used antidepressants remain non-significant in genome-wide case control investigations suggesting no main effect in depression, but rather an interaction with stress. The few significant genes in GWASs are related to neurogenesis, neuronal synapse, cell contact and DNA transcription and as being nonspecific for depression are difficult to harvest pharmacologically. Most candidate genes in replicable gene x environment interactions, on the other hand, are connected to the regulation of stress and the HPA axis and thus could serve as drug targets for depression subgroups characterized by stress-sensitivity and anxiety while other risk polymorphisms such as those related to prominent cognitive symptoms in depression may help to identify additional subgroups and their distinct treatment. Until these new targets find their way into therapy, the optimization of current medications can be approached by pharmacogenomics, where metabolizing enzyme polymorphisms remain prominent determinants of therapeutic success.

Progress in Elucidating Biomarkers of Antidepressant Pharmacological Treatment Response: A Systematic Review and Meta-analysis of the Last 15 Years

BACKGROUND

Antidepressant drugs are widely prescribed, but response rates after 3 months are only around one-third, explaining the importance of the search of objectively measurable markers predicting positive treatment response. These markers are being developed in different fields, with different techniques, sample sizes, costs, and efficiency. It is therefore difficult to know which ones are the most promising.

OBJECTIVE

Our purpose was to compute comparable (i.e., standardized) effect sizes, at study level but also at marker level, in order to conclude on the efficacy of each technique used and all analyzed markers.

METHODS

We conducted a systematic search on the PubMed database to gather all articles published since 2000 using objectively measurable markers to predict antidepressant response from five domains, namely cognition, electrophysiology, imaging, genetics, and transcriptomics/proteomics/epigenetics. A manual screening of the abstracts and the reference lists of these articles completed the search process.

RESULTS

Executive functioning, theta activity in the rostral Anterior Cingular Cortex (rACC), and polysomnographic sleep measures could be considered as belonging to the best objectively measured markers, with a combined d around 1 and at least four positive studies. For inter-category comparisons, the approaches that showed the highest effect sizes are, in descending order, imaging (combined d between 0.703 and 1.353), electrophysiology (0.294-1.138), cognition (0.929-1.022), proteins/nucleotides (0.520-1.18), and genetics (0.021-0.515).

CONCLUSION

Markers of antidepressant treatment outcome are numerous, but with a discrepant level of accuracy. Many biomarkers and cognitions have sufficient predictive value (d ≥ 1) to be potentially useful for clinicians to predict outcome and personalize antidepressant treatment.

The interaction between monoamine oxidase A (MAOA) and childhood maltreatment as a predictor of personality pathology in females: Emotional reactivity as a potential mediating mechanism

Research consistently demonstrates that common polymorphic variation in monoamine oxidase A (MAOA) moderates the influence of childhood maltreatment on later antisocial behavior, with growing evidence that the "risk" allele (high vs. low activity) differs for females. However, little is known about how this Gene × Environment interaction functions to increase risk, or if this risk pathway is specific to antisocial behavior. Using a prospectively assessed, longitudinal sample of females (n = 2,004), we examined whether changes in emotional reactivity (ER) during adolescence mediated associations between this Gene × Environment and antisocial personality disorder in early adulthood. In addition, we assessed whether this putative risk pathway also conferred risk for borderline personality disorder, a related disorder characterized by high ER. While direct associations between early maltreatment and later personality pathology did not vary by genotype, there was a significant difference in the indirect path via ER during adolescence. Consistent with hypotheses, females with high-activity MAOA genotype who experienced early maltreatment had greater increases in ER during adolescence, and higher levels of ER predicted both antisocial personality disorder and borderline personality disorder symptom severity. Taken together, findings suggest that the interaction between MAOA and early maltreatment places women at risk for a broader range of personality pathology via effects on ER.

Sex differences modulating serotonergic polymorphisms implicated in the mechanistic pathways of risk for depression and related disorders

Despite consistent observations of sex differences in depression and related emotional disorders, we do not yet know how these sex differences modulate the effects of genetic polymorphisms implicated in risk for these disorders. This Mini-Review focuses on genetic polymorphisms of the serotonergic system to illustrate how sex differences might modulate the neurobiological pathways involved in the development of depression. We consider the interacting role of environmental factors such as early-life stress. Given limited current knowledge about this topic, we highlight methodological considerations, challenges, and guidelines for future research. © 2016 Wiley Periodicals, Inc.

Serotonergic 5HTTLPR/rs25531 s-allele homozygosity associates with violent suicides in male citalopram users

Depressive disorders are involved as a background factor in over 50% of suicide cases. The most widely used antidepressants today are serotonin selective reuptake inhibitors (SSRIs). However, not all users benefit from SSRI medication. Although the overall number of suicides in Finland have decreased notably during the last decade, the annual rate is still relatively high, particularly in male population. In this study, we tested the hypothesis that the genetic variants associated with decreased citalopram efficiency, 5HTTLPR/rs25531, and increased impulsive behavior, MAOA-uVNTR and HTR2B Q20*, are more frequent among citalopram users committing suicide than among the citalopram users in general. Also the effect of alcohol was evaluated. The study population comprised 349 suicide victims (184 males and 165 females). Based on the suicide method used, cases were divided into two groups; violent (88 males and 49 females) and non-violent (96 males and 116 females). The control group (284; 159 males and 125 females) consisted of citalopram users who died of causes other than suicide. We found that male citalopram users with low functioning s/s genotype of 5HTTLPR/rs25531 were in increased risk to commit violent suicide (OR 2.50, 95%CI 1.15-5.42, p = 0.020). Surprisingly, high blood alcohol concentration was observed to be a risk factor only in non-violent suicides (both males and females), but not in violent ones. No association between suicides and MAOA-uVNTR and HTR2B Q20*, which have been previously connected to violent and impulsive behavior, was detected.

Type A monoamine oxidase and serotonin are coordinately involved in depressive disorders: from neurotransmitter imbalance to impaired neurogenesis

Type A monoamine oxidase (MAOA) catabolizes monoamine transmitters, serotonin, norepinephrine and dopamine, and plays a major role in the onset, progression and therapy of neuropsychiatric disorders. In depressive disorders, increase in MAOA expression and decrease in brain levels of serotonin and norepinephrine are proposed as the major pathogenic factors. The functional polymorphism of MAOA gene and genes in serotonin signal pathway are associated with depression. This review presents recent advance in studies on the role of MAOA in major depressive disorder and related emotional disorders. MAOA and serotonin regulate the prenatal development and postnatal maintenance of brain architecture and neurocircuit, as shown by MAOA-deficient humans and MAO knockout animal models. Impaired neurogenesis in the mature hippocampus has been proposed as "adult neurogenesis" hypothesis of depression. MAOA modulates the sensitivity to stress in the stages of brain development and maturation, and the interaction of gene-environmental factors in the early stage regulates the onset of depressive behaviors in adulthood. Vice versa environmental factors affect MAOA expression by epigenetic regulation. MAO inhibitors not only restore compromised neurotransmitters, but also protect neurons from cell death in depression through induction of anti-apoptotic Bcl-2 and prosurvival neurotrophic factors, especially brain-derived neurotrophic factor, the deficiency of which is detected in depression. This review discusses novel role of MAOA and serotonin in the pathogenesis and therapy of depressive disorders.

Regulation of emotional response in juvenile monkeys treated with fluoxetine: MAOA interactions

Juvenile male rhesus macaques received therapeutic doses of fluoxetine daily from one to three years of age and were compared to vehicle-treated controls (N=16/group). Genotyping for monoamine oxidase A (MAOA) polymorphisms was used to form subgroups (N=8) with high and low expression of the gene. Behavioral responses were scored during 30-second exposures to pictures differing in affective content. As expected from its therapeutic effect, fluoxetine decreased the behavioral response to emotionally evocative pictures. A 44% reduction in number of expressive behaviors was seen, but only in subjects with low expression MAOA polymorphisms. In general, this effect occurred for pictures of varying affective content and was not due to altered occurrence of one specific behavior or type of behavior. The drug*genotype interaction was seen after one and two years of treatment and did not reverse one year after discontinuation of dosing. Two potential translational implications are suggested: (1) MAOA genetic polymorphisms may be the source of some of the variability in response to fluoxetine treatment in children; (2) extended fluoxetine treatment during juvenile brain development may result in persistent effects on emotional regulation.

Analysis of personality traits and their influence on the quality of life of postmenopausal women with regard to genetic factors

BACKGROUND

Quality of life can be perceived as a subjective assessment of different aspects of human functioning. Personality is a factor which determines actions taken by individuals and their tendency to perceive reality in a particular way. Therefore, the assumption that personality may influence the QoL assessment seems reasonable. Our purpose was to assess the relationships between personality traits and the presence of the 44-bp VNTR polymorphism in the 5-HTT (SLC 6A4) promoter region and the 30-bp VNTR polymorphism in the MAO-A promoter region. We also wanted to determine the influence of personality on the quality of life of postmenopausal women.

METHODS

The study involved 214 postmenopausal women from northwest Poland. It was conducted using the NEO-FFI and the SF-36 questionnaires. DNA polymorphisms were identified using the polymerase chain reaction (PCR).

RESULTS

The average age of the women was 56.8 ± 4.08 years. Half of the respondents had completed second-level education, 69.2 % had life partners, and 53.3 % were professionally active. Women with the 3/3 genotype were characterized by significantly lower openness to experience than respondents with other MAO-A genotypes (p < 0.05). There was a significant correlation between the quality of life and the levels of neuroticism and extroversion, as well as between selected quality of life domains and the levels of agreeableness and conscientiousness.

CONCLUSIONS

(1)Women with the 3/3 genotype of the 30-bp VNTR polymorphism in the MAO-A promoter region are characterized by lower levels of openness to experience than women with other MAO-A genotypes in our study (2) Personality traits may contribute to the assessment of the quality of life.

Environmental and genetic determinants of childhood depression: The roles of DAT1 and the antenatal environment

Research on adolescent and adult populations has linked depression to variation in several monoaminergic genes, but genetic association studies on depression in children are limited. Additionally, few studies have investigated whether stressors occurring very early in development moderate the influence of certain genes on depression. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) from monoaminergic genes interacted with measures of early life stress to influence depressive symptoms in children. Participants were members of the Auckland Birthweight Collaborative cohort. Small for gestational age (SGA) and maternal stress during pregnancy were measured at birth and used as indicators of early life stress. At age 11, depressive symptoms were measured using the Centre for Epidemiological Studies Depression Scale for Children (CES-DC) and DNA samples were collected for genotyping. A two-way ANOVA revealed that SGA and a SNP from the dopamine transporter gene DAT1 had an interactive effect on children's depressive symptoms. Specifically, symptoms were greater in children born SGA who are T homozygous for the rs1042098 SNP. These findings suggest that adverse intrauterine environments leading to low birth weight also seem to exacerbate the effects of certain DAT1 variants on depression.

Sleep disturbance as detected by actigraphy in pre-pubertal juvenile monkeys receiving therapeutic doses of fluoxetine

Sleep disturbance is a reported side effect of antidepressant drugs in children. Using a nonhuman primate model of childhood selective serotonin reuptake inhibitor (SSRI) therapy, sleep was studied quantitatively with actigraphy. Two 48-h sessions were recorded in the home cage environment of juvenile male rhesus monkeys at two and three years of age, after one and two years of treatment with a therapeutic dose of the SSRI fluoxetine, and compared to vehicle treated controls. A third session was conducted one year after discontinuation of treatment at four years of age. During treatment, the fluoxetine group demonstrated sleep fragmentation as indexed by a greater number of rest-activity transitions compared to controls. In addition fluoxetine led to more inactivity during the day as indexed by longer duration of rest periods and the reduced activity during these periods. The fluoxetine effect on sleep fragmentation, but not on daytime rest, was modified by the monkey's genotype for polymorphisms of monoamine oxidase A (MAOA), an enzyme that metabolizes serotonin. After treatment, the fluoxetine effect on nighttime rest-activity transitions persisted, but daytime activity was not affected. The demonstration in this nonhuman primate model of sleep disturbance in connection with fluoxetine treatment and specific genetic polymorphisms, and in the absence of diagnosed psychopathology, can help inform use of this drug in children.

Amphetamine manipulates monoamine oxidase-A level and behavior using theranostic aptamers of transcription factors AP-1/NF-kB

BACKGROUND

Monoamine oxidase (MAO) enzymes play a critical role in controlling the catabolism of monoamine neurotransmitters and biogenic trace amines and behavior in humans. However, the mechanisms that regulate MAO are unclear. Several transcription factor proteins are proposed to modulate the transcription of MAO gene, but evidence supporting these hypotheses is controversial. We aimed to investigate the mechanism of gene transcription regulator proteins on amphetamine-induced behavior. We applied aptamers containing a DNA binding sequence, as well as a random sequence (without target) to study the modulation of amphetamine-induced MAO levels and hyperactivity in living mice.

METHODS

We pretreated in adult male C57black6 mice (Taconic Farm, Germantown, NY) (n ≥ 3 litters at a time), 2 to 3 months of age (23 ± 2 gm body weight) with double-stranded (ds) DNA aptamers with sequence specific to activator protein-1 (5ECdsAP1), nuclear factor-kappa beta (5ECdsNF-kB), special protein-1 (5ECdsSP-1) or cyclicAMP responsive element binding (5ECdsCreB) protein binding regions, 5ECdsRan [a random sequence without target], single-stranded AP-1 (5ECssAP-1) (8 nmol DNA per kg) or saline (5 μl, intracerebroventricular [icv] injection) control before amphetamine administration (4 mg/kg, i.p.). We then measured and analyzed locomotor activities and the level of MAO-A and MAO-B activity.

RESULTS

In the pathological condition of amphetamine exposure, we showed here that pretreatment with 5ECdsAP1 and 5ECdsNF-kB reversed the decrease of MAO-A activity (p < 0.05, t test), but not activity of the B isomer (MAO-B), in the ventral tegmental area (VTA) and substantia nigra (SN) of C57black6 mice. The change in MAO-A level coincided with a reversed amphetamine-induced restless behavior of mice. Pretreatments with saline, 5ECdsCreB, 5ECdsSP-1, 5ECdsRan or 5ECssAP-1 had no effect.

CONCLUSION

Our data lead us to conclude that elevation of AP-1 or NF-kB indirectly decreases MAO-A protein levels which, in turn, diminishes MAO-A ability in the VTA of the mesolimbic dopaminergic pathway that has been implicated in cells under stress especially in the SN and VTA. This study has implications for design for the treatment of drug exposure and perhaps Parkinson's dementia.

Serotonin pathway polymorphisms and the treatment of major depressive disorder and anxiety disorders

While antidepressants are widely used to treat major depressive disorder and anxiety disorders, only half of the patients will respond to antidepressant treatment and only a third of patients will experience a remission of symptoms. Identification of genetic biomarkers that predict antidepressant treatment response could thus greatly improve current clinical practice by providing guidance on which drug to use for which patient. Most antidepressant drugs for the treatment of depression and anxiety disorders have effects on the serotonergic neurotransmitter system; thus, genetic polymorphisms in the genes involved in this pathway represent logical candidates for investigation. This article reviews recent findings on the pharmacogenetics of antidepressant drugs with a focus on serotonergic pathway polymorphisms and discusses future clinical applications.

Imaging genetics studies on monoaminergic genes in major depressive disorder

Although depression is the leading cause of disability worldwide, current understanding of the neurobiology of depression has failed to be translated into clinical practice. Major depressive disorder (MDD) pathogenesis is considered to be significantly influenced by multiple risk genes, however genetic effects are not simply expressed at a behavioral level. Therefore the concept of endophenotype has been applied in psychiatric genetics. Imaging genetics applies anatomical or functional imaging technologies as phenotypic assays to evaluate genetic variation and their impact on behavior. This paper attempts to provide a comprehensive review of available imaging genetics studies, including reports on genetic variants that have most frequently been linked to MDD, such as the monoaminergic genes (serotonin transporter gene, monoamine oxidase A gene, tryptophan hydroxylase-2 gene, serotonin receptor 1A gene and catechol-O-methyl transferase gene), with regard to key structures involved in emotion processing, such as the hippocampus, amygdala, anterior cingulate cortex and orbitofrontal cortex.

Regional cortical thinning of the orbitofrontal cortex in medication-naïve female patients with major depressive disorder is not associated with MAOA-uVNTR polymorphism

BACKGROUND

Orbitofrontal cortex alterations have been suggested to underlie the impaired mood regulation in depression. MAOA-uVNTR (monoamine oxidase A-upstream variable number of tandem repeats) polymorphism has been reported to be associated with major depressive disorder by various studies. The influence of MAOA-uVNTR genotype on function and structure of the orbitofrontal cortex has previously been reported. In this study, we investigated the difference in orbitofrontal cortex thickness between medication-naïve female patients with major depressive disorder and healthy controls, and the influence of MAOA-uVNTR genotype on orbitofrontal cortex thickness in depression.

METHODS

Thirty-one patients with major depressive disorder and 43 healthy controls were included. All participants were subjected to T1-weighted structural magnetic resonance imaging and genotyped for MAOA-uVNTR polymorphism. An automated procedure of FreeSurfer was used to analyze difference in orbitofrontal cortex thickness.

RESULTS

Patients showed a significantly thinner left orbitofrontal cortex (F_(1,71) = 7.941, p = 0.006) and right orbitofrontal cortex (F_(1,71) = 17.447, p < 0.001). For the orbitofrontal cortex sub-region analysis, patients showed a significantly thinner left medial orbitofrontal cortex (F_(1,71) = 8.117, p = 0.006), right medial orbitofrontal cortex (F_(1,71) = 21.795, p < 0.001) and right lateral orbitofrontal cortex (F_(1,71) = 9.932, p = 0.002) compared to healthy controls. No significant interaction of diagnosis and MAOA-uVNTR genotype on orbitofrontal cortex thickness was revealed.

CONCLUSIONS

Our results suggest that structural alterations of the orbitofrontal cortex may be associated with the pathophysiology of major depressive disorder. Future studies with larger sample sizes are needed to detect a possible association between MAOA-uVNTR genotype and orbitofrontal cortex thickness in depression.

MAOA Variants and Genetic Susceptibility to Major Psychiatric Disorders

Monoamine oxidase A (MAOA) is a mitochondrial enzyme involved in the metabolism of several biological amines such as dopamine, norepinephrine, and serotonin, which are important neurochemicals in the pathogenesis of major psychiatric illnesses. MAOA is regarded as a functional plausible susceptibility gene for psychiatric disorders, whereas previous hypothesis-driven association studies obtained controversial results, a reflection of small sample size, genetic heterogeneity, or true negative associations. In addition, MAOA is not analyzed in most of genome-wide association studies (GWAS) on psychiatric disorders, since it is located on Chromosome Xp11.3. Therefore, the effects of MAOA variants on genetic predisposition to psychiatric disorders remain obscure. To fill this gap, we collected psychiatric phenotypic (schizophrenia, bipolar disorder, and major depressive disorder) and genetic data in up to 18,824 individuals from diverse ethnic groups. We employed classical fixed (or random) effects inverse variance weighted methods to calculate summary odds ratios (OR) and 95 % confidence intervals (CI). We identified a synonymous SNP rs1137070 showing significant associations with major depressive disorder (p = 0.00067, OR = 1.263 for T allele) and schizophrenia (p = 0.0039, OR = 1.225 for T allele) as well as a broad spectrum of psychiatric phenotype (p = 0.000066, OR = 1.218 for T allele) in both males and females. The effect size was similar between different ethnic populations and different gender groups. Collectively, we confirmed that MAOA is a risk gene for psychiatric disorders, and our results provide useful information toward a better understanding of genetic mechanism involving MAOA underlying risk of complex psychiatric disorders.

Engrailed-2 (En2) deletion produces multiple neurodevelopmental defects in monoamine systems, forebrain structures and neurogenesis and behavior

Many genes involved in brain development have been associated with human neurodevelopmental disorders, but underlying pathophysiological mechanisms remain undefined. Human genetic and mouse behavioral analyses suggest that ENGRAILED-2 (EN2) contributes to neurodevelopmental disorders, especially autism spectrum disorder. In mouse, En2 exhibits dynamic spatiotemporal expression in embryonic mid-hindbrain regions where monoamine neurons emerge. Considering their importance in neuropsychiatric disorders, we characterized monoamine systems in relation to forebrain neurogenesis in En2-knockout (En2-KO) mice. Transmitter levels of serotonin, dopamine and norepinephrine (NE) were dysregulated from Postnatal day 7 (P7) to P21 in En2-KO, though NE exhibited the greatest abnormalities. While NE levels were reduced ∼35% in forebrain, they were increased 40 -: 75% in hindbrain and cerebellum, and these patterns paralleled changes in locus coeruleus (LC) fiber innervation, respectively. Although En2 promoter was active in Embryonic day 14.5 -: 15.5 LC neurons, expression diminished thereafter and gene deletion did not alter brainstem NE neuron numbers. Significantly, in parallel with reduced NE levels, En2-KO forebrain regions exhibited reduced growth, particularly hippocampus, where P21 dentate gyrus granule neurons were decreased 16%, suggesting abnormal neurogenesis. Indeed, hippocampal neurogenic regions showed increased cell death (+77%) and unexpectedly, increased proliferation. Excess proliferation was restricted to early Sox2/Tbr2 progenitors whereas increased apoptosis occurred in differentiating (Dcx) neuroblasts, accompanied by reduced newborn neuron survival. Abnormal neurogenesis may reflect NE deficits because intra-hippocampal injections of β-adrenergic agonists reversed cell death. These studies suggest that disruption of hindbrain patterning genes can alter monoamine system development and thereby produce forebrain defects that are relevant to human neurodevelopmental disorders.

Association study of monoamine oxidase-A gene promoter polymorphism (MAOA-uVNTR) with self-reported anxiety and other psychopathological symptoms in a community sample of early adolescents

The polymorphism upstream of the gene for monoamine oxidase A (MAOA-uVNTR) is reported to be an important enzyme involved in human physiology and behavior. With a sample of 228 early-adolescents from a community sample (143 girls) and adjusting for environmental variables, we examined the influence of MAOA-uVNTR alleles on the scores obtained in the Screen for Childhood Anxiety and Related Emotional Disorders and in the Child Symptom Inventory-4. Our results showed that girls with the high-activity MAOA allele had higher scores for generalized and total anxiety than their low-activity peers, whereas boys with the low-activity allele had higher social phobia scores than boys with the high-activity allele. Results for conduct disorder symptoms did not show a significant relationship between the MAOA alleles and the presence of these symptoms. Our findings support a possible association, depending on gender, between the MAOA-uVNTR polymorphism and psychopathological disorders such as anxiety, which affects high rates of children and adolescents.

An analysis of the influence of selected genetic and hormonal factors on the occurrence of depressive symptoms in late-reproductive-age women

BACKGROUND

The aim of this study was to analyze the influence of genetic and hormonal factors on incidences of depressive symptoms in late-reproductive-age women.

METHODS

The study was performed using the Beck Depression Inventory, the PCR, and genetic tests of 347 healthy late-reproductive-age Polish women.

RESULTS

The relationship between the level of anti-Müllerian hormone (AMH) and depressive symptoms was not statistically significant (p > 0.05). Increases in age and FSH levels were accompanied by a decrease in AMH level in a significant way (p < 0.05). There were no statistically significant relationships between the distribution of genotypes and the frequency of alleles of the investigated polymorphisms and depressive symptoms according to the Beck Depression Inventory.

CONCLUSIONS

(1) The presence of the s/s genotype of the 5-HTTLPR polymorphism in the serotonin transporter promoter region and the 3/3 genotype of the 30-bp VNTR polymorphism in the monoamine oxidase A promoter region does not contribute to the development of depressive symptoms in late-reproductive-age women. (2) A relationship between the level of anti-Müllerian hormone and depressive symptoms was not confirmed in the group of healthy late-reproductive-age women. (3) AMH level correlates negatively with FSH level and age, which confirms that AMH can be regarded as a factor reflecting the ovarian reserve.

COMT and MAO-A polymorphisms and obsessive-compulsive disorder: a family-based association study

Objective

Obsessive-compulsive disorder (OCD) is a common and debilitating psychiatric illness. Although a genetic component contributes to its etiology, no single gene or mechanism has been identified to the OCD susceptibility. The catechol-O-methyltransferase (COMT) and monoamine oxidase A (MAO-A) genes have been investigated in previous OCD studies, but the results are still unclear. More recently, Taylor (2013) in a comprehensive meta-analysis of genetic association studies has identified COMT and MAO-A polymorphisms involved with OCD. In an effort to clarify the role of these two genes in OCD vulnerability, a family-based association investigation was performed as an alternative strategy to the classical case-control design.

Methods

Transmission disequilibrium analyses were performed after genotyping 13 single-nucleotide polymorphisms (eight in COMT and five in MAO-A) in 783 OCD trios (probands and their parents). Four different OCD phenotypes (from narrow to broad OCD definitions) and a SNP x SNP epistasis were also analyzed.

Results

OCD, broad and narrow phenotypes,were not associated with any of the investigated COMT and MAO-A polymorphisms. In addition, the analyses of gene-gene interaction did not show significant epistatic influences on phenotype between COMT and MAO-A.

Conclusions

The findings do not support an association between DSM-IV OCD and the variants of COMT or MAO-A. However, results from this study cannot exclude the contribution of these genes in the manifestation of OCD. The evaluation of broader spectrum phenotypes could help to understand the role of these and other genes in the pathophysiology of OCD and its spectrum disorders.

Monoamine oxidase a gene polymorphisms and bipolar disorder in Iranian population

BACKGROUND

Bipolar disorder (BPD) is a common and severe mood disorder. Although genetic factors have important rolesin the etiology of bipolar disorder, no specific gene has been identified in relation to this disorder. Monoamine oxidase gene is suggested to be associated with bipolar disorder in many studies.

OBJECTIVES

This study aimed to investigatethe role of MAOA gene polymorphisms in the etiology of bipolar disorder in Iranian population.

PATIENTS AND METHODS

This study is a case-control study, with convenient sampling. Three common polymorphisms, a CA microsatellite, a VNTR, and a RFLP were typed in 156 bipolar patients and 173 healthy controls. Patients were chosen from Imam Hossein General Hospital, Psychiatry Ward (Tehran/Iran). Controlsamples for this study consisted of 173 healthy individuals recruitedby convenient sampling. Allelic distributions of these polymorphisms were analyzed in bipolar and control groups to investigate any association with MAOA gene.

RESULTS

Significant associations were observed regarding MAOA-CA (P = 0.016) and MAOA-VNTR (P = 0.004) polymorphisms in the bipolar females. There was no association between MAOA-RFLP and bipolar disorder.

CONCLUSIONS

The obtained results confirm some previous studies regardinga gender specific association of MAOA gene with the bipolar disorder.

Advances in biomarkers of major depressive disorder

Major depressive disorder (MDD) is characterized by mood, vegetative, cognitive, and even psychotic symptoms and signs that can cause substantial impairments in quality of life and functioning. Biomarkers are measurable indicators that could help diagnosing MDD or predicting treatment response. In this chapter, lipid profiles, immune/inflammation, and neurotrophic factor pathways that have long been implicated in the pathogenesis of MDD are discussed. Then, pharmacogenetics and epigenetics of serotonin transport and its metabolism pathway, brain-derived neurotrophic factor, and abnormality of hypothalamo-pituitary-adrenocortical axis also revealed new biomarkers. Lastly, new techniques, such as proteomics and metabolomics, which allow researchers to approach the studying of MDD with new directions and make new discoveries are addressed. In the future, more data are needed regarding pathophysiology of MDD, including protein levels, single nucleotide polymorphism, epigenetic regulation, and clinical data in order to better identify reliable and consistent biomarkers for diagnosis, treatment choice, and outcome prediction.

Evaluation of the relationship between 5-HTT and MAO gene polymorphisms, mood and level of anxiety among postmenopausal women

Objective: The aim of this study was to analyze how mood and anxiety level are related to the functional genetic polymorphism in the promoter region of SLC6A4 (5-HTTLPR) and the 30-bp VNTR polymorphism in the MAO A promoter region. Methods: The study involved 272 postmenopausal women from Poland. The authors employed the State-Trait Anxiety Inventory for measuring levels of anxiety, the Mood Adjective Check List for measuring mood, and genetic tests. Results: Analysis did not show any statistically significant differences in the mean levels of anxiety, and mood disorders in women in relation to genotypes of the 5-HTTLPR (SLC6A4) polymorphism and the 30-bp VNTR polymorphism in the MAO A promoter region. However, these problems were more severe among women with s/s genotype. In the case of MAO A gene polymorphism, the level of anxiety was higher in women with a 4/4 genotype. Conclusions: The study did not prove the possibility of the identification of homogeneous groups of women with an elevated risk of developing anxiety and mood disorders during the post-menopausal period. Nevertheless, it showed that respondents with s/s genotype of the 44-bp polymorphism in the 5-HTT (SLC6A4) promoter region had the highest average anxiety levels both as a state and as a trait. Furthermore, the analysis of the 30-bp VNTR polymorphism in the MAO A promoter region demonstrated slight differences in anxiety levels between the women, indicating that those with a 4/4 genotype had higher severity of anxiety symptoms.

Biological determinants of depression following bereavement

There is considerable variability among people in their response to bereavement. While most people adapt well to bereavement, some develop exaggerated and/or pathological responses and may meet criteria for a major depressive episode. Many studies have investigated the effect of psychosocial factors on bereavement outcome but biological factors have not received much attention, hence the focus of this paper. The biological factors studied to date in relation to bereavement outcomes include genetic polymorphisms, neuroendocrine factors, and immunologic/inflammatory markers. In addition, animal studies have shown the alterations of brain neurotransmitters as well as changes in the plasma levels of the neurotrophic growth factors under the influence of peer loss. Recent studies have also investigated the biological basis of stress resilience, and have found a few genetic polymorphisms and potential biomarkers as protective factors in the face of adversity. Longitudinal studies that include data collection prior to, and also after, bereavement and which chart both biological and psychological measures are needed to develop profiles for the prediction of response to bereavement and personalised interventions.

Fluoxetine: juvenile pharmacokinetics in a nonhuman primate model

RATIONALE

The selective serotonin reuptake inhibitor (SSRI) fluoxetine is the only psychopharmacological agent approved for use in children. While short-term studies of side effects have been performed, long-term consequences for brain development are not known. Such studies can be performed in appropriate animal models if doses modeling therapeutic use in children are known.

OBJECTIVES

The goal of this study was to identify a daily dose of fluoxetine in juvenile monkeys which would result in serum fluoxetine and norfluoxetine concentrations in the therapeutic range for children.

METHODS

Juvenile (2.5-year-old rhesus monkeys, n = 6) received single administration of doses of 1, 2, and 4 mg/kg day fluoxetine on a background of chronic dosing at an intermediate level to provide steady-state conditions to model therapeutic administration. Using nonlinear modeling, standard pharmacokinetic parameters were derived. Cerebrospinal fluid monoamine neurotransmitters were assayed to confirm the pharmacological effects.

RESULTS

Dose-dependent area under the curve (AUC) and C max values were seen, while T max and absorption/elimination half-lives were minimally influenced by dose. A dosage of 2 mg/kg day given over a 14-week period led to steady-state serum concentrations of active agent (fluoxetine + norfluoxetine) similar to those recorded from drug monitoring studies in children. Cisternal cerebrospinal fluid concentrations of serotonin increased significantly over the 14-week period, while concentrations of the serotonin metabolite (5-HIAA) were lower but not significantly different.

CONCLUSIONS

A dose of 2 mg/kg day fluoxetine in juvenile rhesus monkeys provides an internal dose similar to therapeutic use in children and will help establish a valuable animal model for understanding fluoxetine's therapeutic and potential adverse effects in children.

Preadoption adversity, MAOA, and behavioral adjustment in internationally adopted Chinese girls

OBJECTIVES

We studied postinstitutionalized adopted Chinese girls to determine whether those with different variants of the MAOA gene promoter region (MAOA-VNTR) differed in their internalizing and externalizing behavior problems and whether the MAOA genotype moderated the relation between preadoption adversity and current behavior problems.

METHODS

MAOA genotyping was obtained for 94 girls (mean age: 9.2 years) and the number of 4-repeat (4R) alleles was determined (zero, one, or two). The adoptive mothers rated several indicators of preadoption adversity shortly after adoption (mean age at adoption 15.8 months) and completed the Child Behavior Checklist when the children were 8.1 years on average.

RESULTS

No main effects were found for preadoption adversity. However, the MAOA genotype had a nominally significant effect (P<0.05) on internalizing problems. Regression analyses controlling for age, household income, authoritarian parenting, and family problems showed that among children with no physical signs of preadoption adversity, those carrying a greater number of 4R alleles scored significantly lower (P<0.01) on internalizing problems than those with fewer 4R alleles. Differences in internalizing scores related to the MAOA genotype were not observed for children who showed one or more physical signs of adversity at the time of adoption. A similar pattern was found for externalizing problems, although the results did not reach conventional levels of significance.

CONCLUSION

Our results suggest that higher MAOA activity may be protective with respect to internalizing problems in internationally adopted Chinese girls, but that this protective effect decreases at higher levels of preadoption adversity. A similar pattern may exist for externalizing problems.

Monoamine oxidase A suppresses hepatocellular carcinoma metastasis by inhibiting the adrenergic system and its transactivation of EGFR signaling

BACKGROUND & AIMS

Monoamine oxidase A (MAOA), a catecholamine neurotransmitter degrading enzyme, is closely associated with neurological and psychiatric disorders. However, its role in cancer progression remains unknown.

METHODS

Hepatocellular carcinoma (HCC) tissue arrays (n=254) were used to investigate the correlation between MAOA expression and clinicopathological findings. In vitro invasion and anoikis assays, and in vivo intrahepatic and lung metastasis models were used to determine the role of MAOA in HCC metastasis. Quantitative real-time PCR, western blotting, immunohistochemical staining and HPLC analysis were performed to uncover the mechanism of MAOA in HCC.

RESULTS

We found that MAOA expression was significantly downregulated in 254 clinical HCC samples and was closely correlated with cancer vasoinvasion, metastasis, and poor prognoses. We then demonstrated that MAOA suppressed norepinephrine/epinephrine (NE/E)-induced HCC invasion and anoikis inhibition, and uncovered that the effects of NE/E on HCC behaviors were primarily mediated through alpha 1A (ADRA1A) and beta 2 adrenergic receptors (ADRB2). In addition to the canonical signaling pathway, which is mediated via adrenergic receptors (ADRs), we found that ADR-mediated EGFR transactivation was also involved in NE-induced HCC invasion and anoikis inhibition. Notably, we found that MAOA could synergize with EGFR inhibitors or ADR antagonists to abrogate NE-induced HCC behaviors.

CONCLUSIONS

Taken together, the results of our study may provide insights into the application of MAOA as a novel predictor of clinical outcomes and indicate that increasing MAOA expression or enzyme activity may be a new approach that can be used for HCC treatment.

Pharmacoepigenetics of depression: no major influence of MAO-A DNA methylation on treatment response

The monoamine oxidase A (MAO-A) gene has been suggested to be involved in the pathogenesis as well as the pharmacological treatment of major depressive disorder. In the present analysis, for the first time a pharmacoepigenetic approach was applied investigating the influence of DNA methylation patterns in the MAO-A regulatory and exon1/intron1 region on antidepressant treatment response. 94 patients of Caucasian descent with major depressive disorder (f = 61; DSM-IV) were analyzed for DNA methylation status at 43 MAO-A CpG sites via direct sequencing of sodium bisulfite treated DNA extracted from blood cells. Patients were also genotyped for the functional MAO-A VNTR. Clinical response to antidepressant treatment with escitalopram was assessed by intra-individual changes of HAM-D-21 scores after 6 weeks of treatment. Apart from two CpG sites, male subjects showed no or only very minor methylation. In female patients, lower methylation at two individual CpG sites in the MAO-A promoter region was nominally associated with impaired response to antidepressant treatment after 6 weeks (GRCh37/hg19: CpG 43.514.063, p = 0.04; CpG 43.514.684, p = 0.009), not, however, withstanding correction for multiple testing. MAO-A VNTR genotypes did not influence MAO-A methylation status. The present pilot data do not suggest a major influence of MAO-A DNA methylation on antidepressant treatment response. However, the presently observed trend towards CpG-specific MAO-A gene hypomethylation-possibly via increased gene expression and consecutively decreased serotonin and/or norepinephrine availability-to potentially drive impaired antidepressant treatment response in female patients might be worthwhile to be followed up in larger pharmacoepigenetic studies.