Serotonin Transporter Gene Polymorphisms and Selective Serotonin Reuptake Inhibitor Tolerability: Review of Pharmacogenetic Evidence

Racial and Ethnic Considerations for the Clinical Practice of Psychopharmacology and Research Methodology: A Narrative Review of the Growing Body of Literature

BACKGROUND

Race and ethnicity are important but often underexamined factors in psychopharmacology research and clinical practice. This review summarizes key findings on ethnic and racial considerations for researchers, medical practitioners, and clinical psychopharmacologists. We hope it serves an important function in highlighting a critically important, yet still emerging issue to inform research and therapeutic use of psychotropics to improve their effectiveness.

METHODS

We queried major databases (PubMed, PsycInfo, Embase) using a search strategy that included MeSH (Medical Subject Headings) terms and conducted a snowball search to identify studies addressing ethnic or racial aspects of psychopharmacological practice. Findings were synthesized and presented in clinically applicable areas.

RESULTS

The clinically relevant ethnic and racial considerations identified in this review can be broadly categorized into the following areas: (1) variations in therapeutic and adverse dose-responses (eg, non-Whites attaining therapeutic and adverse effects at lower doses with certain medications); (2) interracial differences in prescription patterns of psychotropics, with lower prescription rates among under-represented minority groups and greater use of first-generation antipsychotics in African American populations; and (3) variations in attitudes toward psychopharmacotherapy. While differences in medication response can be partially explained by genetic variations in metabolism or receptor sensitivity, systemic racism and social determinants of health continue to have an influence.

CONCLUSIONS

The evidence base for ethnic and racial considerations in psychopharmacology research and clinical practice continues to evolve with growing consideration for diversity and inclusivity in training, research, and clinical practice. This is critical to promoting equitable and effective care to a diverse population. Key questions are highlighted to draw attention to these critical needs.

[Pharmacogenomic and pharmacometabolomic biomarkers of the efficacy and safety of antidepressants: focus on selective serotonin reuptake inhibitors]

The efficacy and safety of psychopharmacotherapy with antidepressants is of great medical importance. The search for clinical and biological predictors for choosing the optimal psychopharmacotherapy with antidepressants is actively underway all over the world. Research is mainly devoted to searching for associations of polymorphic gene variants with the efficacy and safety of therapy. However, information about a patient's genetic polymorphism is often insufficient to predict the efficacy and safety of a drug. Modern research on the personalization of pharmacotherapy should include, in addition to genetic, phenotypic biomarkers. This is important because genotyping, for example, cannot accurately predict the actual metabolic activity of an isoenzyme. To personalize therapy, a combination of methods is required to obtain the most complete profile of the efficacy and safety of the drug. Successful treatment of depression remains a challenge, and inter-individual differences in response to antidepressants are common. About half of patients with depressive disorders do not respond to the first attempt at antidepressant therapy. Serious side-effects of antidepressant pharmacotherapy and discontinuation of treatment due to their intolerance are associated with ineffective therapy. This review presents the results of the latest studies of «omics» biomarkers of the efficacy and safety of antidepressants.

The Role of Pharmacogenetics in Personalizing the Antidepressant and Anxiolytic Therapy

Pharmacotherapy for neuropsychiatric disorders, such as anxiety and depression, has been characterized by significant inter-individual variability in drug response and the development of side effects. Pharmacogenetics, as a key part of personalized medicine, aims to optimize therapy according to a patient's individual genetic signature by targeting genetic variations involved in pharmacokinetic or pharmacodynamic processes. Pharmacokinetic variability refers to variations in a drug's absorption, distribution, metabolism, and elimination, whereas pharmacodynamic variability results from variable interactions of an active drug with its target molecules. Pharmacogenetic research on depression and anxiety has focused on genetic polymorphisms affecting metabolizing cytochrome P450 (CYP) and uridine 5'-diphospho-glucuronosyltransferase (UGT) enzymes, P-glycoprotein ATP-binding cassette (ABC) transporters, and monoamine and γ-aminobutyric acid (GABA) metabolic enzymes, transporters, and receptors. Recent pharmacogenetic studies have revealed that more efficient and safer treatments with antidepressants and anxiolytics could be achieved through genotype-guided decisions. However, because pharmacogenetics cannot explain all observed heritable variations in drug response, an emerging field of pharmacoepigenetics investigates how epigenetic mechanisms, which modify gene expression without altering the genetic code, might influence individual responses to drugs. By understanding the epi(genetic) variability of a patient's response to pharmacotherapy, clinicians could select more effective drugs while minimizing the likelihood of adverse reactions and therefore improve the quality of treatment.

Evidence Regarding Pharmacogenetics in Pain Management and Cancer

Patients experience interindividual variation in response to analgesics, which may be partially explained by genetics. This commentary discusses a recently published trial on COMT genotype and opioid dose requirements and describes the potential role for COMT and other genes (eg, CYP2D6) on opioid therapy and the current evidence for germline pharmacogenetics and resources for opioid pharmacogenetics.

Safety and Efficacy of SSRIs in Improving Poststroke Recovery: A Systematic Review and Meta-Analysis

Background Several studies investigated the role of selective serotonin reuptake inhibitors (SSRIs) in improving poststroke recovery; thus, we have decided to conduct this systematic review and meta-analysis to investigate the efficacy and safety of SSRIs in poststroke recovery. Methods and Results In this meta-analysis we searched the following databases: PubMed, Cochrane, Scopus, and Google Scholar. The studies were included if they were placebo-controlled trials in design and reported SSRIs' effects on poststroke depression, anxiety, disability, dependence, motor abilities, and cognitive functions. The quality of the included studies was assessed using the revised Cochrane risk-of-bias tool for randomized trials. The search yielded 44 articles that included 16 164 patients, and about half of the participants were treated with SSRIs. Our results showed that SSRIs had a significant effect on preventing depression (weighted mean difference [WMD], -7.05 [95% CI, -11.78 to -2.31]), treating depression according to the Hamilton Rating Scale for Depression score (WMD, -1.45 [95% CI, -2.77 to -0.14]), anxiety (relative risk, 0.23 [95% CI, 0.09-0.61]), dependence (WMD, 8.86 [95% CI, 1.23-16.48]), motor abilities according to National Institutes of Health Stroke Scale score (WMD, -0.79 [95% CI, -1.42 to -0.15]), and cognitive functions (WMD, 1.00 [95% CI, 0.12-1.89]). On the other hand, no significant effect of SSRIs on disability was observed. Additionally, we found that treating with SSRIs increased the risk of seizures (relative risk, 1.44 [95% CI, 1.13-1.83]), whereas there was no difference in the incidence of gastrointestinal symptoms or bleeding between SSRIs and a placebo. Conclusions Our study showed that SSRIs are effective in preventing and treating depression, and improving anxiety, motor function, cognitive function, and dependence in patients after stroke. These benefits were only reproducible with the citalopram subanalysis but not fluoxetine. Further well-conducted placebo-controlled trials are needed to investigate the safety and efficacy of citalopram among patients after stroke. Registration URL: www.crd.york.ac.uk/prospero/; Unique identifier: CRD42021285766.

An Updated Review of Genetic Associations With Severe Adverse Drug Reactions: Translation and Implementation of Pharmacogenomic Testing in Clinical Practice

Adverse drug reactions (ADR) remain the major problems in healthcare. Most severe ADR are unpredictable, dose-independent and termed as type B idiosyncratic reactions. Recent pharmacogenomic studies have demonstrated the strong associations between severe ADR and genetic markers, including specific HLA alleles (e.g., HLA-B*15:02/HLA-B*57:01/HLA-A*31:01 for carbamazepine-induced severe cutaneous adverse drug reactions [SCAR], HLA-B*58:01 for allopurinol-SCAR, HLA-B*57:01 for abacavir-hypersensitivity, HLA-B*13:01 for dapsone/co-trimoxazole-induced SCAR, and HLA-A*33:01 for terbinafine-induced liver injury), drug metabolism enzymes (such as CYP2C9*3 for phenytoin-induced SCAR and missense variant of TPMT/NUDT15 for thiopurine-induced leukopenia), drug transporters (e.g., SLCO1B1 polymorphism for statin-induced myopathy), and T cell receptors (Sulfanilamide binding into the CDR3/Vα of the TCR 1.3). This mini review article aims to summarize the current knowledge of pharmacogenomics of severe ADR, and the potentially clinical use of these genetic markers for avoidance of ADR.

Precision medicine in mood disorders

The choice of the most appropriate psychoactive medication for each of our patients is always a challenge. We can use more than 100 psychoactive drugs in the treatment of mood disorders, which can be prescribed either alone or in combination. Response and tolerability problems are common, and much trial and error is often needed before achieving a satisfactory outcome. Precision medicine is therefore needed for tailoring treatment to optimize outcome. Pharmacological, clinical, and demographic factors are important and informative, but biological factors may further inform and refine prediction. Twenty years after the first reports of gene variants modulating antidepressant response, we are now confronted with the prospect of routine clinical pharmacogenetic applications in the treatment of depression. The scientific community is divided into two camps: those who are enthusiastic and those who are skeptical. Although it appears clear that the benefit of existing tools is still not completely defined, at least in the case of central nervous system gene variants, this is not the case for metabolic gene variants, which is generally accepted. Cumulative scores encompassing many variants across the entire genome will soon predict psychiatric disorder liability and outcome. At present, precision medicine in mood disorders may be implemented using clinical and pharmacokinetic factors. In the near future, a genome-wide composite genetic score in conjunction with clinical factors within each patient is the most promising approach for developing a more effective way to target treatment for patients suffering from mood disorders.

Pharmacogenomics-Guided Pharmacotherapy in Patients with Major Depressive Disorder or Bipolar Disorder Affected by Treatment-Resistant Depressive Episodes: A Long-Term Follow-Up Study

Treatment-resistant depression (TRD) reduces affected patients' quality of life and leads to important social health care costs. Pharmacogenomics-guided treatment (PGT) may be effective in the cure of TRD. The main aim of this study was to evaluate the clinical changes after PGT in patients with TRD (two or more recent failed psychopharmacological trials) affected by bipolar disorder (BD) or major depressive disorder (MDD) compared to a control group with treatment as usual (TAU). We based the PGT on assessing different gene polymorphisms involved in the pharmacodynamics and pharmacokinetics of drugs. We analyzed, with a repeated-measure ANOVA, the changes between the baseline and a 6 month follow-up of the efficacy index assessed through the Clinical Global Impression (CGI) scale, and depressive symptoms through the Hamilton Depression Rating Scale (HDRS). The PGT sample included 53 patients (26 BD and 27 MDD), and the TAU group included 52 patients (31 BD and 21 MDD). We found a significant within-subject effect of treatment time on symptoms and efficacy index for the whole sample, with significant improvements in the efficacy index (F = 8.544; partial η² = 0.077, p < 0.004) and clinical global impression of severity of illness (F = 6.818; partial η² = 0.062, p < 0.01) in the PGT vs. the TAU group. We also found a significantly better follow-up response (χ² = 5.479; p = 0.019) and remission (χ² = 10.351; p = 0.001) rates in the PGT vs. the TAU group. PGT may be an important option for the long-term treatment of patients with TRD affected by mood disorders, providing information that can better define drug treatment strategies and increase therapeutic improvement.

Serotonin Transporter Genetic Variation and Antidepressant Response and Tolerability: A Systematic Review and Meta-Analysis

Antidepressants are used to treat several psychiatric disorders; however, a large proportion of patients do not respond to their first antidepressant therapy and often experience adverse drug reactions (ADR). A common insertion–deletion polymorphism in the promoter region (5-HTTLPR) of the serotonin transporter (SLC6A4) gene has been frequently investigated for its association with antidepressant outcomes. Here, we performed a systematic review and meta-analysis to assess 5-HTTLPR associations with antidepressants: (1) response in psychiatric disorders other than major depressive disorder (MDD) and (2) tolerability across all psychiatric disorders. Literature searches were performed up to January 2021, yielding 82 studies that met inclusion criteria, and 16 of these studies were included in the meta-analyses. Carriers of the 5-HTTLPR LL or LS genotypes were more likely to respond to antidepressant therapy, compared to the SS carriers in the total and European ancestry-only study populations. Long (L) allele carriers taking selective serotonin reuptake inhibitors (SSRIs) reported fewer ADRs relative to short/short (SS) carriers. European L carriers taking SSRIs had lower ADR rates than S carriers. These results suggest the 5-HTTLPR polymorphism may serve as a marker for antidepressant outcomes in psychiatric disorders and may be particularly relevant to SSRI treatment among individuals of European descent.

Pediatric Therapeutic Drug Monitoring for Selective Serotonin Reuptake Inhibitors

Therapeutic drug monitoring (TDM) is uncommon in child and adolescent psychiatry, particularly for selective serotonin reuptake inhibitors (SSRIs)—the first-line pharmacologic treatments for depressive and anxiety disorders. However, TDM in children and adolescents offers the opportunity to leverage individual variability of antidepressant pharmacokinetics to shed light on non-response and partial response, understand drug-drug interactions, evaluate adherence, and characterize the impact of genetic and developmental variation in pharmacokinetic genes. This perspective aims to educate clinicians about TDM principles and examines evolving uses of TDM in SSRI-treated youths and their early applications in clinical practice, as well as barriers to TDM in pediatric patients. First, the impact of pharmacokinetic genes on SSRI pharmacokinetics in youths could be used to predict tolerability and response for some SSRIs (e.g., escitalopram). Second, plasma concentrations are significantly influenced by adherence, which may relate to decreased efficacy. Third, pharmacometric analyses reveal interactions with proton pump inhibitors, oral contraceptives, cannabinoids, and SSRIs in youths. Rapid developments in TDM and associated modeling have enhanced the understanding of variation in SSRI pharmacokinetics, although the treatment of anxiety and depressive disorders with SSRIs in youths often remains a trial-and-error process.

Genetic variants associated with cardiometabolic abnormalities during treatment with selective serotonin reuptake inhibitors: a genome-wide association study

Selective serotonin reuptake inhibitors (SSRIs) are prescribed both to patients with schizophrenia and bipolar disorder. Previous studies have shown associations between SSRI treatment and cardiometabolic alterations. The aim of the present study was to investigate genetic variants associated with cardiometabolic adverse effects in patients treated with SSRIs in a naturalistic setting, using a genome-wide cross-sectional approach in a genetically homogeneous sample. We included and genotyped 1981 individuals with schizophrenia or bipolar disorder, of whom 1180 had information available on the outcomes low-density lipoprotein cholesterol (LDL-cholesterol), high-density lipoprotein cholesterol (HDL-cholesterol), triglycerides, and body mass index (BMI) and investigated interactions between SNPs and SSRI use (N = 246) by conducting a genome-wide GxE analysis. We report 13 genome-wide significant interaction effects of SNPs and SSRI serum concentrations on LDL-cholesterol, HDL-cholesterol, and BMI, located in four distinct genomic loci. This study provides new insight into the pharmacogenetics of SSRI but warrants replication in independent populations.

Physiology and Pharmacology of Neurotransmitter Transporters

Regulation of the ability of a neurotransmitter [our focus: serotonin, norepinephrine, dopamine, acetylcholine, glycine, and gamma-aminobutyric acid (GABA)] to reach its receptor targets is regulated in part by controlling the access the neurotransmitter has to receptors. Transporters, located at both the cellular plasma membrane and in subcellular vesicles, carry a myriad of responsibilities that include enabling neurotransmitter release and controlling uptake of neurotransmitter back into a cell or vesicle. Driven largely by electrochemical gradients, these transporters move neurotransmitters. The regulation of the transporters themselves through changes in expression and/or posttranslational modification allows for fine-tuning of this system. Transporters have been best recognized as targets for psychoactive stimulants and remain a mainstay target of primarily central nervous system (CNS) acting drugs for treatment of debilitating diseases such as depression and anxiety. Studies reveal, however, that transporters are found and functional in tissues outside the CNS (gastrointestinal and cardiovascular tissues, for example). The importance of neurotransmitter transporters is underscored with discoveries that dysfunction of transporters can cause life-changing disease. This article provides a high-level review of major classes of both plasma membrane transporters and vesicular transporters. © 2021 American Physiological Society. Compr Physiol 11:2279-2295, 2021.

Depressive Symptoms are Associated with low Serotonin Levels in Plasma but are not 5-HTTLPR Genotype Dependent in Older Adults

Depressive symptoms are diagnosed by physicians using scales but their pathophysiology is unclear. Low serotonin (5-HT) levels play an important role in depression, and the 5-HT transporter (5-HTT) is an important regulator of plasma serotonin levels and reuptake. Additionally, the 5-HTT gene-linked polymorphic region (5-HTTLPR) is associated with depression. The aim was to clarify the roles of plasma serotonin levels in plasma and the 5HTTPLR polymorphism in depressive symptoms in older adults. A total of 84 older adult participants were evaluated. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale of 20 items (CESD-20). The plasma serotonin levels were determined by ELISA, and the 5-HTTLPR genotype was analyzed by PCR. Depressive symptoms were present in 39.3% (N = 33) of the participants. The median plasma serotonin level was 204.34 ng/mL (SD = 93.88). A significant correlation was found between the CESD-20 scale and plasma serotonin levels (r = -.256; p = .019). Low serotonin levels were associated with the presence of depressive symptoms (p = .001). The 5-HTTLPR analysis showed that of the 84 older adults, 35.7% had the SS genotype, 10.7% had the LL genotype, and 53.6% were heterozygous. The 5-HTTLPR polymorphism was not associated with depressive symptoms (p = .587) and plasma serotonin levels (p = 0.391). Depressive symptoms correlate with low serotonin levels in plasma, but not with the 5-HTTLPR polymorphism in older Mexican adults.

Treatment-Resistant Depression Revisited: A Glimmer of Hope

Major Depressive Disorder (MDD) is a highly prevalent psychiatric disorder worldwide. It causes individual suffering, loss of productivity, increased health care costs and high suicide risk. Current pharmacologic interventions fail to produce at least partial response to approximately one third of these patients, and remission is obtained in approximately 30% of patients. This is known as Treatment-Resistant Depression (TRD). The burden of TRD exponentially increases the longer it persists, with a higher risk of impaired functional and social functioning, vast losses in quality of life and significant risk of somatic morbidity and suicidality. Different approaches have been suggested and utilized, but the results have not been encouraging. In this review article, we present new approaches to identify and correct potential causes of TRD, thereby reducing its prevalence and with it the overall burden of this disease entity. We will address potential contributory factors to TRD, most of which can be investigated in many laboratories as routine tests. We discuss endocrinological aberrations, notably, hypothalamic-pituitary-adrenal (HPA) axis dysregulation and thyroid and gonadal dysfunction. We address the role of Vitamin D in contributing to depression. Pharmacogenomic testing is being increasingly used to determine Single Nucleotide Polymorphisms in Cytochrome P450, Serotonin Transporter, COMT, folic acid conversion (MTHFR). As the role of immune system dysregulation is being recognized as potentially a major contributory factor to TRD, the measurement of C-reactive protein (CRP) and select immune biomarkers, where testing is available, can guide combination treatments with anti-inflammatory agents (e.g., selective COX-2 inhibitors) reversing treatment resistance. We focus on established and emerging test procedures, potential biomarkers and non-biologic assessments and interventions to apply personalized medicine to effectively manage treatment resistance in general and TRD specifically.

Pharmacogenetic/Pharmacogenomic Tests for Treatment Prediction in Depression

Genetic factors play a significant but complex role in antidepressant (AD) response and tolerability. During recent years, there is growing enthusiasm in the promise of pharmacogenetic/pharmacogenomic (PGx) tools for optimizing and personalizing treatment outcomes for patients with major depressive disorder (MDD). The influence of pharmacokinetic and pharmacodynamic genes on response and tolerability has been investigated, including those encoding the cytochrome P450 superfamily, P-glycoprotein, monoaminergic transporters and receptors, intracellular signal transduction pathways, and the stress hormone system. Genome-wide association studies are also identifying new genetic variants associated with AD response phenotypes, which, combined with methods such as polygenic risk scores (PRS), is opening up new avenues for novel personalized treatment approaches for MDD. This chapter describes the basic concepts in PGx of AD response, reviews the major pharmacokinetic and pharmacodynamic genes involved in AD outcome, discusses PRS as a promising approach for predicting AD efficacy and tolerability, and addresses key challenges to the development and application of PGx tests.

Post-traumatic Stress Symptoms and Serotonin Transporter (5-HTTLPR) Polymorphism in Breast Cancer Patients

Introduction: Post-traumatic Symptoms (PTSS) and Post-traumatic Stress Disorder (PTSD) have been reported to affect a quite significant proportion of cancer patients. No study has examined the relationship between serotonin transporter gene-linked polymorphic region (5-HTTLPR) and cancer, including Gene-Environment interactions between this polymorphism and specific causes of distress, such as cancer related problems (CRP) or life stressful events (SLE). Methods: One hundred and forty five breast cancer outpatients participated in the study and were assessed using the Impact of Event Scale (IES), the Problem List (PL) developed by the National Comprehensive Cancer Network (NCCN) Distress Management Guidelines and the Paykel's Life Events Interview to evaluate the exposure to SLE during the year before the cancer diagnosis. Each patient was genotyped for 5-HTTLPR polymorphism by analyzing genomic DNA obtained from whole blood cells. Gene-Environment interactions were tested through moderation analysis. Results: Twenty-six patients (17.7%) were classified as PTSS cases using the IES. Genotype and phenotype distributions did not differ across individuals with/without PTSS (genotype: χ² = 1.5; df = 2; p = 0.3; phenotype χ² = 0.9; df = 1; p = 0.2). For both the genotype and phenotype model, using CRP as a predictor showed significant gene-environment interactions with IES total score (p = 0.020 and p = 0.004, respectively), with individuals carrying the l/l allele showing a greater probability of experiencing PTSS. No interaction was found in relationship to SLE (p = 0.750). Conclusion: This study showed a significant GEI between CRP and PTSS in breast cancer patients, with carriers of the l/l allele showing indicators consistent with greater sensitivity to stress.

The Structure and Mechanism of Drug Transporters

Drug transporters are integral membrane proteins that play a critical role in drug disposition by affecting absorption, distribution, and excretion. They translocate drugs, as well as endogenous molecules and toxins, across membranes using ATP hydrolysis, or ion/concentration gradients. In general, drug transporters are expressed ubiquitously, but they function in drug disposition by being concentrated in tissues such as the intestine, the kidneys, the liver, and the brain. Based on their primary sequence and their mechanism, transporters can be divided into the ATP-binding cassette (ABC), solute-linked carrier (SLC), and the solute carrier organic anion (SLCO) superfamilies. Many X-ray crystallography and cryo-electron microscopy (cryo-EM) structures have been solved in the ABC and SLC transporter superfamilies or of their bacterial homologs. The structures have provided valuable insight into the structural basis of transport. This chapter will provide particular focus on the promiscuous drug transporters because of their effect on drug disposition and the challenges associated with them.

COVID-19 impacts the expression of molecular markers associated with neuropsychiatric disorders

Coronavirus disease 2019 (COVID-19) was initially characterized due to its impacts on the respiratory system; however, many recent studies have indicated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) significantly affects the brain. COVID-19 can cause neurological complications, probably caused by the induction of a cytokine storm, since there is no evidence of neurotropism by SARS-CoV-2. In line with this, the COVID-19 outbreak could accelerate the progression or affect the clinical outcomes of neuropsychiatric conditions. Thus, we analyzed differential gene expression datasets for clinical samples of COVID-19 patients and identified 171 genes that are associated with the pathophysiology of the following neuropsychiatric disorders: alcohol dependence, autism, bipolar disorder, depression, panic disorder, schizophrenia, and sleep disorder. Several of the genes identified are associated with causing some of these conditions (classified as elite genes). Among these elite genes, 9 were found for schizophrenia, 6 for autism, 3 for depression/major depressive disorder, and 2 for alcohol dependence. The patients with the neuropsychiatric conditions associated with the genes identified may require special attention as COVID-19 can deteriorate or accelerate neurochemical dysfunctions, thereby aggravating clinical outcomes.

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COVID-19 can impact the clinical outcomes of neuropsychiatric diseases (NP).

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Molecular markers of NP were differentially expressed in patients with COVID-19.

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Elite genes were found for schizophrenia, autism, depression and alcohol dependence.

Antidepressant-Associated Mania in Bipolar Disorder: A Review and Meta-analysis of Potential Clinical and Genetic Risk Factors

PURPOSES/BACKGROUND

Antidepressants (ADs) play a valuable role in treating the depressive episodes of bipolar disorder. However, 14% of these individuals taking ADs experience AD-associated mania (AAM) within a few weeks of starting treatment. Numerous studies have suggested potential clinical and genetic risk factors. We aimed to conduct a comprehensive systematic review and meta-analysis that integrates the past literature with the recent studies and identifies important predictors for AAM.

METHODS/PROCEDURES

The review was limited to experimentally designed studies that contain the relevant search terms in PubMed and PsychInfo. After removing studies that were in discordance with our criteria, the review included 24 reports examining clinical risk factors and 10 investigating genetic risk factors. Our meta-analysis was conducted on 5 clinical risk factors, each of which had at least 4 articles with extractable data.

FINDINGS/RESULTS

The only clinical factors in the literature that have been shown to be more indicative of AAM risk are AD monotherapy and tricyclic ADs. Among genetic factors, the serotonin transporter gene polymorphism may play a minor role in AAM. Our meta-analysis provided support for the number of prior depressive episodes.

IMPLICATIONS/CONCLUSION

Prevention of AAM may be served by early detection of recurrent depression episodes. Further large-scale longitudinal studies are required to determine the underpinnings of AAM.

5HTTLPR Genetic Variant and Major Depressive Disorder: A Review

Major Depressive Disorder (MDD) is a disease that involves biological, psychological, and social interactions. Studies have shown the importance of genetics contribution to MDD development. The SCL6A4 protein (5HTTLPR) functions transporting serotonin, a neurotransmitter linked to mood and emotion, to the synaptic cleft. Hence, this study seeks, through a literature review, a better comprehension of the 5HTTLPR genetic variant association with MDD. For this purpose, a search was performed on the Virtual Health Library Portal for articles that related 5HTTLPR to MDD. Most of the articles found were conducted in the American continent, with one (1) study implemented in Brazil. 5HTTLPR associations were found regarding changes in the nervous system, pharmacology, and risk factors seen in MDD patients. When verifying the allelic distribution, the S allele had a higher frequency in most of the studies analyzed. Despite not finding a commonality in the different studies, the tremendous genetic variation found demonstrates the MDD complexity. For this reason, further studies in diverse populations should be conducted to assist in the understanding and treatment of the disease.

The search for personalized antidepressant treatments: what have we learned and where are we going

Over 20 years after the initial report of gene variants within the central nervous system modulating antidepressant response, we are now facing for the first time routine clinical pharmacogenetic applications. The scientific community is divided between enthusiasm and skepticism. It seems clear that the benefit of existing tools is not huge, at least for the central nervous system gene variants, while it is generally accepted for the metabolic gene variants. Findings from large international consortia suggest for the first time in psychiatric genetic research history that cumulative scores comprising many variants across the whole genome may reliably constitute liability factors for psychiatric disorders, this approach will most likely improve also present pharmacogenetic tools. A composite genetic score complemented with clinical risk factors for each patient is the most promising approach for a more effective method of targeted treatment for patients with depression.

Neuroendocrine neoplasia of the gastrointestinal tract revisited: towards precision medicine

Over the past 5 years, a number of notable research advances have been made in the field of neuroendocrine cancer, specifically with regard to neuroendocrine cancer of the gastrointestinal tract. The aim of this Review is to provide an update on current knowledge that has proven effective for the clinical management of patients with these tumours. For example, for the first time in the tubular gastrointestinal tract, well-differentiated high-grade (grade 3) tumours and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are defined in the WHO classification. This novel classification enables efficient identification of the most aggressive well-differentiated neuroendocrine tumours and helps in defining the degree of aggressiveness of MiNENs. The Review also discusses updates to epidemiology, cell biology (including vesicle-specific components) and the as-yet-unresolved complex genetic background that varies according to site and differentiation status. The Review summarizes novel diagnostic instruments, including molecules associated with the secretory machinery, novel radiological approaches (including pattern recognition techniques), novel PET tracers and liquid biopsy combined with DNA or RNA assays. Surgery remains the treatment mainstay; however, peptide receptor radionuclide therapy with novel radioligands and new emerging medical therapies (including vaccination and immunotherapy) are evolving and being tested in clinical trials, which are summarized and critically reviewed here.

Pharmacogenetics of anxiety disorders

Anxiety disorders are common and disabling conditions the treatment of which remains a challenge. While different groups of medication are available for their treatment, a substantial proportion of patients remain refractory to pharmacotherapy. The reason for this variation in the individual response to treatment has yet to be understood; however genetic factors have been shown to play an important role. Up to now there have been limited publications about pharmacogenetics of anxiety disorders, compared to studies in depression. Published studies are focused on pharmacogenetics of antidepressants rather than being disease specific. This review summarizes pharmacogenetic findings related to the anxiolytic treatment response and their possible functional mechanisms. This inevitably focuses on genes involved in the pharmacodynamics of the medications used, along with some genes implicated in the disease process, as well as briefly mentioning genetic factors associated with psychotherapeutic response.

Translational Studies in the Complex Role of Neurotransmitter Systems in Anxiety and Anxiety Disorders

Discovery of innovative anxiolytics is severely hampering. Existing anxiolytics are developed decades ago and are still the therapeutics of choice. Moreover, lack of new drug targets forecasts a severe jeopardy in the future treatment of the huge population of CNS-diseased patients. We simply lack the knowledge on what is wrong in brains of anxious people (normal and diseased). Translational research, based on interacting clinical and preclinical research, is extremely urgent. In this endeavor, genetic and genomic approaches are part of the spectrum of contributing factors. We focus on three druggable targets: serotonin transporter, 5-HT_1A, and GABA_A receptors. It is still uncertain whether and how these targets are involved in normal and diseased anxiety processes. For serotonergic anxiolytics, the slow onset of action points to indirect effects leading to plasticity changes in brain systems leading to reduced anxiety. For GABA_A benzodiazepine drugs, acute anxiolytic effects are found indicating primary mechanisms directly influencing anxiety processes. Close translational collaboration between fundamental academic and discovery research will lead to badly needed breakthroughs in the search for new anxiolytics.

Rare variants in SLC6A4 cause susceptibility to major depressive disorder with suicidal ideation in Han Chinese adolescents and young adults

BACKGROUND

Suicidal ideation (SI) is the most serious symptom of major depressive disorder (MDD) and considered an extreme state. The serotonin transporter gene (SLC6A4) plays a significant role in MDD and suicide pathophysiology. Previous studies have revealed an association between common variants of SLC6A4 with the risk of MDD and suicide. However, very few studies have so far focused on the degree to which rare variants of SLC6A4 are responsible for the depression observed in adolescent and young adult suicide patients. The aim of this study was to examine the impact of common and rare variants of SLC6A4 on the risk of Han Chinese adolescents and young adults suffering MDD with SI.

METHODS

Targeted sequencing of the SLC6A4 gene was conducted using FastTarget technology in Han Chinese adolescents and young adults, of which 74 were MDD patients with SI and 150 were healthy controls. Gene-based association analyses of rare variants were performed using enrichment analysis and a cumulative allele test. An allele association study was performed against common variants.

RESULTS

After sequencing and bioinformatics analysis, a total of 15 single nucleotide variants (SNVs) were detected in the targeted regions from all participants, including 9 common and 6 rare variants. Among these, 5 rare variants were identified within the study group. Enrichment analysis of rare variants demonstrated a statistical difference (p = 0.042) between the study and control groups. Using cumulative allele analysis, alternative alleles in the SLC6A4 gene exhibited an association with MDD patients with SI (cumulative allele: OR = 10.18, 95% CI = 1.18-87.32, p = 0.017). No significant association was found between the 9 common SLC6A4 variants and MDD patients with SI.

CONCLUSIONS

Our results suggest that rare variants of SLC6A4 may contribute to a genetic risk of adolescents and young adults suffering MDD with SI.

Influence of CYP2C19 Metabolizer Status on Escitalopram/Citalopram Tolerability and Response in Youth With Anxiety and Depressive Disorders

In pediatric patients, the selective serotonin reuptake inhibitors (SSRIs) escitalopram and citalopram (es/citalopram) are commonly prescribed for anxiety and depressive disorders. However, pharmacogenetic studies examining CYP2C19 metabolizer status and es/citalopram treatment outcomes have largely focused on adults. We report a retrospective study of electronic medical record data from 263 youth < 19 years of age with anxiety and/or depressive disorders prescribed escitalopram or citalopram who underwent routine clinical CYP2C19 genotyping. Slower CYP2C19 metabolizers experienced more untoward effects than faster metabolizers (p = 0.015), including activation symptoms (p = 0.029) and had more rapid weight gain (p = 0.018). A larger proportion of slower metabolizers discontinued treatment with es/citalopram than normal metabolizers (p = 0.007). Meanwhile, faster metabolizers responded more quickly to es/citalopram (p = 0.005) and trended toward less time spent in subsequent hospitalizations (p = 0.06). These results highlight a disparity in treatment outcomes with es/citalopram treatment in youth with anxiety and/or depressive disorders when standardized dosing strategies were used without consideration of CYP2C19 metabolizer status. Larger, prospective trials are warranted to assess whether tailored dosing of es/citalopram based on CYP2C19 metabolizer status improves treatment outcomes in this patient population.

NEUROPSYCHOBIOLOGICAL MECHANISMS OF AFFECTIVE AND COGNITIVE DISORDERS IN THE CHORNOBYL CLEAN-UP WORKERS TAKING INTO ACCOUNT THE SPECIFIC GENE POLYMORPHISMS

Relevance of the present work is determined by the considerable prevalence of both affective and cognitive disor-ders in the victims due to the Chornobyl accident, the pathogenesis of which is insufficiently studied.Objective is to identify the neuropsychiobiological mechanisms of the formation of the remote affective and cog-nitive disorders following exposure to ionizing radiation taking into account the specific gene polymorphisms.Design, object and methods of research. The retrospective and prospective cohort study with the external andinternal control groups. The randomized sample of the male participants in liquidation of the consequences of theaccident (Chornobyl clean-up workers, liquidators) at the Chornobyl nuclear power plant (ChNPP) in 1986-1987(n = 198) recruited from the Clinico-epidemiological registry (CER) of NRCRM aged 39-87 (M ± SD: 60.0-8.5 years)with the external irradiation dose ranged 0.6-5900.0 mSv (M ± SD: 456.0 ± 760.0 mSv) was examined. The compar-ison group (n = 110) consisted of the unexposed patients of the Radiation Psychoneurology Department with thecorresponding age and sex (the external control group). The internal control group included the liquidators irradi-ated at doses < 50.0 mSv (n = 42). The standard diagnostic neuropsychiatric scales, psychodiagnostic questionnairesand tests, neuropsychological methods (including the Wechsler Adult Intelligence Scale (WAIS) with premorbid IQ(pre-IQ) assessment), neuropsychiatric and psychophysiological methods (quantitative EEG (qEEG) and the audito-ry cognitive evoked potentials (Event-Related Potentials, ERP) were applied. The genotypes of the serotonin trans-porter gene SLC6A4 were determined by the 5_HTTLPR and rs25531 polymorphisms. The methods of descriptive and vari-ation statistics, non-parametric criteria, regression-correlation analysis, survival analysis by Kaplan - Meier and riskanalysis were used.Results. Cerebrovascular diseases, organic mental and depressive disorders, mainly of radiation-stress-relatednature, prevail among the liquidators. The overall risk of neuropsychiatric pathology increases (Pv < 0.001) with theirradiation dose. The verbal memory and learning are impaired, as well as the full IQ is reduced at the expense of theverbal one. The frequency of both mild cognitive impairment and dementia is risen. The cognitive impairment atdoses > 0.3 Sv is dose-dependent (r = 0.4-0.7; p = 0.03-0.003). Affective disorders (depression) and neurocogni-tive deficit are more severe at higher doses of irradiation (> 50 mSv). In the left posterior temporal region(Wernicke's area) the qEEG indices changes become dose-dependent at doses greater than 0.25-0.3 Sv. The dis-turbed brain information processes lateralized to the Wernicke's area are observed even at doses > 50 mSv. The car-riers of intermediate and low-level genotypes (LА/S, LА/LG, LG/LG, LG/S, S/S) of the serotonin transporter gene SLC6A4have more depressive disorders, especially severe ones, and tend to have more frequent and severe cognitive andstress-related disorders.The debut of depressive disorders in the carriers of the intermediate and low-activity genotypes occurs much earli-er (Log-Rank Test = 4.43, p = 0.035) in comparison with the carriers of the high-performance genotype LА/ LА.Conclusions. The radiation-induced dysfunction of the cortico-limbic system in the left dominant hemisphere ofthe human brain with a specific involvement of the hippocampus is considered to be the key cerebral basis of post-radiation organic brain damage. The association of genotypes by 5_HTTLPR and rs25531 polymorphisms of the SLC6A4gene with affective and cognitive disorders suggests the presence of neuropsychobiological features of these dis-orders associated with ionizing radiation depending on the certain gene polymorphisms.

Pharmacogenetic guidelines and decision support tools for depression treatment: application to late-life

Late-life depression (LLD) is a major depressive disorder that affects someone after the age of 60 years. LLD is frequently associated with inadequate response and remission from antidepressants, in addition to polypharmacy. Pharmacogenetics offers a promising approach to improve clinical outcomes in LLD via new discoveries determining the genetic basis of response rates and side effects, as well as the development of tailored pharmacogenetic-based decision support tools. This invited review evaluates the LLD pharmacogenetic evidence base and the extent to which this was incorporated into existing commercial decision support tools and clinical pharmacogenetic guidelines.

5-HTTLPR and MTHFR 677C>T polymorphisms and response to yoga-based lifestyle intervention in major depressive disorder: A randomized active-controlled trial

BACKGROUND

There is growing evidence suggesting that both genetic and environmental factors modulate treatment outcome in, a highly heterogeneous, major depressive disorder (MDD). 5-HTTLPR variant of the serotonin transporter gene (SLC6A4) and MTHFR 677C>T polymorphisms have been linked to the pathogenesis of MDD, and antidepressant treatment response. The evidence is lacking on the clinical utility of yoga in patients with MDD who have 5-HTTLPR and MTHFR 677C>T polymorphisms and less likely to respond to medications (SSRIs).

AIMS

We aimed to examine the impact of YBLI in those who have susceptible 5-HTTLPR and MTHFR 677C>T polymorphisms and are less likely to drug therapy with SSRIs.

SETTINGS AND DESIGN

In a 12 week randomized active-controlled trial, MDD patients (n = 178) were randomized to receive YBLI or drug therapy.

METHODS

Genotyping was conducted using PCR-based methods. The clinical remission was defined as BDI-II score ≤ 9.

STATISTICAL ANALYSIS USED

An intent-to-treat analysis was performed, and the association of genotype with treatment remission consisted of the logistic regression model. A P value of <0.05 was considered statistically significant.

RESULTS

Multivariate logistic regression models for remission including either 5-HTTLPR or MTHFR 677C>T genotypes showed statistically significant odds of remission in YOGA arm vs. DRUG arm. Neither 5-HTTLPR nor MTHFR 677C>T genotype showed any influence on remission to YBLI (P = 0.73 and P = 0.64, respectively). Further analysis showed childhood adversity interact with 5-HTTLPR and MTHFR 677C>T polymorphisms to decrease treatment response in DRUG treatment arm, but not in YOGA arm.

CONCLUSIONS

YBLI provides MDD remission in those who have susceptible 5-HTTLPR and MTHFR 677C>T polymorphisms and are resistant to SSRIs treatment. YBLI may be therapeutic for MDD independent of heterogeneity in its etiopathogenesis.

Fatal intoxication with antidepressants: a case with many culprits

Serotonin-specific reuptake inhibitors (SSRIs) are generally considered safe drugs but fatal adverse effects do sometimes occur, often as a consequence of interactions with other serotonin active drugs. Polypharmacy is usually a problem that the elderly encounter, but it can also have dire consequences for young people, especially when an underlying heart condition is present. Thus, failure to diagnose heart disease and the use of contraindicated medications can be a lethal combination, irrespective of age. Here we present a case of a young adult suffering from bipolar disorder who used a combination of two SSRIs (citalopram and fluoxetine) and a monoamine oxidase inhibitor (MAO; moclobemide) with tragic consequences. The deceased also suffered from undiagnosed hypertrophic cardiomyopathy and was carrier of a genotype that may have predisposed him to increased sensitivity to SSRIs. The apparent difficulty in establishing the manner of death in this case is also discussed.