Mode of inheritance in mood disorder families according to fluvoxamine response

Interactions of childhood maltreatment and genetic variations in adult depression: A systematic review

Background Childhood maltreatment (CM) significantly increases the risk of adulthood psychopathology. Interplay between susceptible genetic variations and CM contributes to the occurrence of depression. This review aims to systematically synthesize the relationships between genetic variations and depression among those exposed to CM. Methods Electronic databases and gray literature to March 31st, 2020 were searched for literature on the topic of depression and CM limited to English-language. Data extraction and quality assessment of key study characteristics were conducted. Qualitative approaches were used to synthesize the findings. Results The initial search resulted in 9185 articles. A total of 29 articles that met the eligibility criteria were included in this review. High heterogeneity was identified regarding the study sample ages, candidate genes and SNPs, the categorization of CM and depression. The findings of this review include several frequently studied genes (5-HTTLPR, CRHR1, BDNF, CREB1, FKBP5, IL1B, NTRK2, and OXTR). Both consistent and inconsistent findings were identified. Overall, the interplay of CM with CREB1-rs2253206 significantly increased the risk of depression. In contrast, CRHR1-TCA haplotype (rs7209436, rs4792887, rs110402), CRHR1-rs17689882, and CRHR1-rs110402 showed protective effects on depression and depressive symptoms among individuals with a history of maltreatment. Limitations Due to clinical and methodological diversity of the studies a qualitative approach was used. Conclusion This review firstly provides a comprehensive overview of the interplay between CM and genetic variations in adult depression. Future etiological explorations should focus on the above-identified genes for down-stream exploration and address the issues and challenges of gene by environment studies.

Response to sertraline is influenced by GNβ3 gene G-350A variant in patients with major depressive disorder

PURPOSE

Heterotrimeric guanine nucleotide-binding proteins (G proteins) are a major group of human genome membrane protein receptors. Genetic variation in the β3 subunit (GNβ3) associated with gene splicing and increased activity is associated with major depressive disorder (MDD). However, the effect of G-350A GNβ3 genetic polymorphism and therapeutic outcome of selective serotonin reuptake inhibitors (SSRIs) in MDD has not yet been studied.

METHOD

One hundred newly diagnosed MDD patients were treated with sertraline for 6 weeks. The severity of depressive symptoms was weekly assessed by Hamilton Rating Scale for Depression (HRSD). A 50% decrease in HRSD was defined as response to treatment. GNβ3 polymorphisms (G-350A, A657T) were determined in each individual using a PCR-RFLP technique.

RESULTS

Our results suggested that subjects with GG genotype of G-350A responded 5.9-folds more to sertraline compared to carriers of other variants (P = 0.004, OR = 5.9; 95% CI = 1.66-21.99). In addition, carriers of the G allele responded 1.9-folds more to sertraline than carriers of the A allele (P = 0.032, OR = 1.92; 95% CI = 1.05-3.65). However, no association was observed between A657T variants and response to sertraline (P = 0.920, OR = 0.9; 95% CI = 0.31-2.69).

CONCLUSION

The results suggest that G-350A variant of GNβ3 plays a foremost part as a predictor of response to antidepressant treatment.

A Preliminary Study of Genetic Variation in the Dopaminergic and Serotonergic Systems and Genome-wide Additive Genetic Effects on Depression Severity and Treatment Response

Major depression is a heritable disorder that is commonly treated with selective serotonin reuptake inhibitors. However, no study has quantified the overlap in genetic effects between pretreatment depression severity and treatment response and the extent to which genetic effects could be attributed to variation in the dopaminergic and serotonergic systems (DA/5-HT). Data (N=1618) from the clinician-rated Hamilton Rating Scale of Depression and the clinician-rated Quick Inventory of Depressive Symptomatology were obtained from participants of European ancestry in the Sequenced Treatment Alternatives to Relieve Depression clinical trial. Genetic variants explained 31%–64% of the variance across assessments of pretreatment depression severity and treatment response. However, effects from the DA/5-HT systems genes were negligible. There was also limited evidence for genetic overlap for pretreatment depression severity and treatment response. Despite the clear genetic contributions to these depression phenotypes, different genetic factors may contribute to depression severity and treatment response.

Pharmacogenomic predictors of citalopram treatment outcome in major depressive disorder

OBJECTIVES

A significant proportion of patients with major depressive disorder (MDD) do not improve following treatment with first-line antidepressants and, currently, there are no objective indicators of predictors of antidepressant response. The aim of this study was to investigate pre-treatment peripheral gene expression differences between future remitters and non-responders to citalopram treatment and identify potential pharmacogenomic predictors of response.

METHODS

We conducted a gene expression study using Affymetrix HG-U133 Plus2 microarrays in peripheral blood samples from untreated individuals with MDD (N = 77), ascertained at a community outpatient clinic, prior to an 8-week treatment with citalopram. Gene expression differences were assessed between remitters and non-responders to treatment. Technical validation of significant probesets was carried out by qRT-PCR.

RESULTS

A total of 434 probesets displayed significant correlation to change in score and 33 probesests were differentially expressed between eventual remitters and non-responders. Probesets for SMAD 7 (SMA- and MAD-related protein 7) and SIGLECP3 (sialic acid-binding immunoglobulin-like lectin, pseudogene 3) were the most significant differentially expressed genes following FDR correction, and both were down-regulated in individuals who responded to treatment.

CONCLUSIONS

These findings point to SMAD7 and SIGLECP3 as candidate predictive biomarkers of antidepressant response.

From pharmacogenetics to pharmacogenomics: the way toward the personalization of antidepressant treatment

OBJECTIVE

Major depressive disorder is the most common psychiatric disorder, worldwide, yet response and remission rates are still unsatisfactory. The identification of genetic predictors of antidepressant (AD) response could provide a promising opportunity to improve current AD efficacy through the personalization of treatment. The major steps and findings along this path are reviewed together with their clinical implications and limitations.

METHOD

We systematically reviewed the literature through MEDLINE and Embase database searches, using any word combination of "antidepressant," "gene," "polymorphism," "pharmacogenetics," "genome-wide association study," "GWAS," "response," and "adverse drug reactions." Experimental works and reviews published until March 2012 were collected and compared.

RESULTS

Numerous genes pertaining to several functional systems were associated with AD response. The more robust findings were found for the following genes: solute carrier family 6 (neurotransmitter transporter), member 4; serotonin receptor 1A and 2A; brain-derived neurotrophic factor; and catechol-O-methyltransferase. Genome-wide association studies (GWASs) provided many top markers, even if none of them reached genome-wide significance.

CONCLUSIONS

AD pharmacogenetics have not produced any knowledge applicable to routine clinical practice yet, as results were mainly inconsistent across studies. Despite this, the rising awareness about methodological deficits of past studies could allow for the identication of more suitable strategies, such as the integration of the GWAS approach with the candidate gene approach, and innovative methodologies, such as pathway analysis and study of depressive endophenotypes.

Pharmacogenetics in major depression: a comprehensive meta-analysis

A number of candidate gene studies focused on major depression (MD) and antidepressant (AD) efficacy have been carried out, but results mainly remain inconclusive. We performed a comprehensive meta-analysis of published candidate gene studies focused on AD efficacy in MD to evaluate the cumulative evidence. A random-effect model was applied to study the polymorphisms with genotypic counts available from at least three independent studies. On the base of previous evidence, the analysis was stratified by ethnicity (Caucasian, Asian, and other/mixed), and AD class (SSRIs and mixed/other ADs). Genotypic data were available for 16 polymorphisms in 11 genes. After the exclusion of 5-HTTLPR in SLC6A4 included in another recent meta-analysis, 15 polymorphisms in 11 genes were included in the present meta-analysis (BDNF rs6265, SLC6A4 STin2, HTR1A rs6295, HTR2A rs6311, rs6313 and rs7997012, HTR6 rs1805054, TPH1 rs1800532, SLC6A2 rs5569, COMT rs4680, GNB3 rs5443, FKBP5 rs1360780 and rs3800373, and ABCB1 rs1045642 and rs2032582). Our results suggested that BDNF rs6265 (Val66Met) heterozygous genotype was associated with better SSRIs response compared to the homozygous genotypes, particularly in Asians (OR=1.53, 95%CI 1.12-2.07, p=0.007). SLC6A4 STin2, HTR2A rs6311 and rs7997012, GNB3 rs5443, FKBP5 rs1360780 and rs3800373, and ABCB1 rs2032582 showed associations with AD efficacy, but these results were highly dependent on one or two single studies. In conclusion, our findings suggested the BDNF Val66Met as the best single candidate involved in AD response, with a selective effect on SSRI treatment. Our overall results supported no major effect of any single gene variant on AD efficacy.

Early antidepressant efficacy modulation by glutamatergic gene variants in the STAR*D

The glutamatergic system has been suggested as a modulator of rapid antidepressant response. Thus, 44 glutamatergic genes were selected according to the literature and investigated in 1541 major depressive patients from the STAR*D genome wide dataset. Outcomes of interest were early response (2nd week) and late response (from the 4th to the 14th week) compared to non-response and stability of response through the STAR*D level 1. A complete agglomerative clustering, based on pairwise identity-by-state (IBS) matrix, was applied in order to control for genetic admixture. A chi-square test was employed as exploratory analysis and a logistic regression was employed to corroborate SNPs associated to the outcomes at p<0.001. Covariates were selected accordingly to their impact on phenotypes. A Bonferroni correction was applied. PLINK served for the analysis. About 1995 SNPs were available after quality control. Our results suggested that the rs1083801 within the GRM7 (glutamate receptor, metabotropic 7) gene was associated to early response under a recessive model (GG genotype observed in 14.34% of early responders vs 5.25% of late responders, OR=0.33, 95% CI=0.21-0.54, p=6.41e-06. GG genotype observed in 5.34% of non-responders, OR=0.33, 95% CI=0.20-0.56, p=4.07e-05). The result was confirmed in the white non-Hispanic group (GG genotype observed in 17.46% of early responders vs 5.81% of the rest of the sample, OR=0.29, 95% CI=0.18-0.46, p=2.04e-07). No marker predicted the stability of response. Glutamatergic genes may be useful markers of early antidepressant efficacy. This result may be relevant in further understanding the pathophysiology of the drug induced antidepressant effect.

Meta-analysis of serotonin transporter gene promoter polymorphism (5-HTTLPR) association with antidepressant efficacy

In the last decade the serotonin transporter gene promoter polymorphism (5-HTTLPR) was likely the most studied genetic variant as predictor of antidepressant response. Nevertheless results are not consistent across studies and previous meta-analysis, since various factors seem to modulate its effect on antidepressant response. With the aim of clarifying this issue, we systematically reviewed literature, selecting 33 studies for an exploratory analysis without any a priori hypothesis. Then we analyzed separately 19 studies performed on Caucasians and 11 on Asians. We tested two phenotypes--remission and response rates--and three genotype comparisons--ll versus ls/ss, ss versus ll/ls and ll versus ss - using the Cochrane review manager. Evaluations were performed separately for SSRIs and mixed/other drugs. Possible clinical modulators were investigated. In the exploratory analysis, we found an association between l allele and l/l genotype and remission. When the analysis was split for ethnic group, in Caucasians we found an association between l allele and both response (OR = 1.58, C.I. 1.16-2.16, p = 0.004), and remission (OR = 1.53, C.I. 1.14-2.04, p = 0.004) in the SSRI group. Only a marginal association between l allele and remission (OR = 1.41, C.I. 1.02-1.95, p = 0.04) survived pooling together mixed antidepressant treatments. In Asians, a small effect of 5-HTTLPR on remission for mixed antidepressants was detected (OR = 2.10, C.I. 1.15-3.84, p = 0.02). Gender, age and age at onset modulated the association in Caucasians. Gender, age and depression severity at baseline modulated the association in Asians. In conclusion, in Caucasians 5-HTTLPR may be a predictor of antidepressant response and remission, while in Asians it does not appear to play a major role.

Association between serotonin transporter gene promoter-region polymorphism and 4- and 12-week treatment response to sertraline in posttraumatic stress disorder

BACKGROUND

We examined the association between serotonin transporter (5HTTLPR) genotype (SS vs SL vs LL) and sertraline treatment outcome in posttraumatic stress disorder (PTSD).

METHODS

Outpatients (n=330) with PTSD underwent 5HTTLPR genotyping. All patients received sertraline (100 mg/day) for 12 weeks. Patients were assessed using the Clinician-Administered PTSD Scale (CAPS) and other instruments. Patients and rater were blind to the genotyping results. The primary outcome was completer sample CAPS improvement at 12 weeks. Response was defined as ≥30% improvement in CAPS total score with a CGI-I score of 1 or 2.

RESULTS

The discontinuation rate was 31.5%. Adverse events led to drop out in 18.1%, 15.3%, and 5.9% of SS, SL, and LL patients, respectively (P=0.038). Among completers, there were 95, 43, and 88 patients with the SS, SL, and LL genotypes, respectively. At endpoint, CAPS total scores improved by 26% vs 46%, respectively, in SS and SL vs LL patients (P<0.001); much of this improvement (15% vs 31% in SS and SL vs LL patients, respectively; P<0.001) was apparent by week 4. The findings were largely similar for the other outcome measures. The response rate was 0%, 0%, and 47.7% in the SS, SL, and LL groups, respectively (P<0.001).

LIMITATIONS

We administered a fixed dose of sertraline. For sociopolitical reasons, we planned a completer analysis only.

CONCLUSIONS

Relative to the SS and SL 5HTTLPR genotypes, the LL genotype is associated with greater responsiveness of PTSD to sertraline (100mg/day) and with lower drop out due to adverse events. The S allele is associated with a striking specificity for treatment nonresponse, as defined in this study.

Gene expression biomarkers of response to citalopram treatment in major depressive disorder

There is significant variability in antidepressant treatment outcome, with ∼30-40% of patients with major depressive disorder (MDD) not presenting with adequate response even following several trials. To identify potential biomarkers of response, we investigated peripheral gene expression patterns of response to antidepressant treatment in MDD. We did this using Affymetrix HG-U133 Plus2 microarrays in blood samples, from untreated individuals with MDD (N=63) ascertained at a community outpatient clinic, pre and post 8-week treatment with citalopram, and used a regression model to assess the impact of gene expression differences on antidepressant response. We carried out technical validation of significant probesets by quantitative reverse transcriptase PCR and conducted central nervous system follow-up of the most significant result in post-mortem brain samples from 15 subjects who died during a current MDD episode and 11 sudden-death controls. A total of 32 probesets were differentially expressed according to response to citalopram treatment following false discovery rate correction. Interferon regulatory factor 7 (IRF7) was the most significant differentially expressed gene and its expression was upregulated by citalopram treatment in individuals who responded to treatment. We found these results to be concordant with our observation of decreased expression of IRF7 in the prefrontal cortex of MDDs with negative toxicological evidence for antidepressant treatment at the time of death. These findings point to IRF7 as a gene of interest in studies investigating genomic factors associated with antidepressant response.

Psychiatric comorbidity and suicide risk in patients with chronic migraine

The aim of this study was to explore the impact of mental illness among patients with migraine. We performed MedLine and PsycINFO searches from 1980 to 2008. Research has systematically documented a strong bidirectional association between migraine and psychiatric disorders. The relationship between migraine and psychopathology has often been clinically discussed rather than systematically studied. Future research should include sound methodologically-based studies focusing on the interplay of factors behind the relationship between migraine, suicide risk, and mental illness.

Pharmacogenomics of antidepressant drugs

While antidepressant pharmacotherapy is an effective treatment of depression, it is still hampered by the slow onset of appreciable clinical improvement and a series of side effects. Moreover, a substantial group of patients does not achieve remission or fails to respond at all. One possible source accounting for these variations in treatment outcome are genetic differences. In recent years a number of pharmacogenetic studies on antidepressant drugs have been published. This manuscript summarizes findings related to the pharmacogenetics of genes involved in the pharmacokinetics as well as pharmacodynamics of antidepressants to date. Illustrated by examples from current candidate gene- and whole genome association studies, this manuscript critically discusses aspects of pharmacogenetic studies in antidepressant response related to study design and clinical relevance.

ABCB1 (MDR1) gene polymorphisms are associated with the clinical response to paroxetine in patients with major depressive disorder

Variability in antidepressant response is due to genetic and environmental factors. Among genetic factors, the ones controlling for availability of the drug at the target site are interesting candidates. Multidrug resistance 1 (ABCB1, MDR1) gene encodes a blood-brain barrier transporter P-glycoprotein that plays an important role in controlling the passage of substances between the blood and brain. In the present study, we therefore examined the possible association of 3 functional ABCB1 polymorphisms (C3435T: rs1045642, G2677T/A: rs2032582 and C1236T: rs1128503) with response to paroxetine in a Japanese major depression sample followed for 6 weeks. Analysis of covariance at week 6 with baseline scores included in the model as covariate showed significant association of the non-synonymous SNP G2677T/A with treatment response to paroxetine (p=0.011). Furthermore, the wild variants haplotype (3435C-2677G-1236T) resulted associated with poor response (p=0.006). To our best knowledge, this study is the first suggestion of a possible association of ABCB1 variants with SSRIs response.

Serotonin transporter gene polymorphism and treatment response to serotonin reuptake inhibitor (escitalopram) in depression: An open pilot study

BACKGROUND

Blocking of the serotonin transporter is the main mechanism of action of SSRIs; therefore, the gene encoding this protein is a strong candidate for a possible genetic influence on the treatment response.

AIM

To evaluate relationship between serotonin transporter gene promoter region polymorphism and the efficacy of SSRI (escitalopram) treatment in depression.

MATERIALS AND METHODS

Fifty-seven consecutive patients with unipolar depressive episode (DSM IV criteria) were genotyped for the SERT gene polymorphism and treated with escitalopram 20 mg/day. Weekly assessment (HAM-D-21) was made for treatment response up to 6 weeks.

RESULTS

Significant (P > 0.0001) difference between groups (ll vs. ss or ls) in response to treatment by escitalopram was revealed by our study. However, no difference with respect to age, gender, or onset of illness was observed between genotype subgroups.

CONCLUSION

The study suggests that serotonin transporter gene polymorphism may have an influence on the effectiveness of SSRI treatment in depressive disorders, irrespective of clinical variables. Further controlled studies are required to validate these results.

Heat-shock protein-70 genes and response to antidepressants in major depression

In the search of predictors of antidepressant efficacy, much interest has recently focused on pro-inflammatory proteins, as they were found to be elevated during major depressives states and decreased by antidepressant drugs. In the present paper we investigated the role of the genes coding for heat-shock-70 family proteins, recently hypothesized to be activated by antidepressants and thus mediate the reduction of pro-inflammatory cytosines. One hundred and forty two hospitalised patients, affected by major depression and treated with antidepressants drugs for a major depressive episode were evaluated for depressive severity at the baseline and at the discharge and genotyped for five SNPs within the genes HSPA1L, HSPA1A and HSPA1B. Markers were not individually associated with symptom severity after treatment. Instead, we found a three markers haplotype, including SNPs within HSPA1L and HSPA1A, associated with a poorer response to antidepressant treatment (p=0.005). Single markers as well as haplotypes were not associated with other clinical features. In conclusion, genetic variants within the genes coding for HSP-70 family proteins may affect the action of antidepressants and thus their therapeutic efficacy.

Dissecting the determinants of depressive disorders outcome: an in depth analysis of two clinical cases

Clinicians face everyday the complexity of depression. Available pharmacotherapies and psychotherapies improve patients suffering in a large part of subjects, however up to half of patients do not respond to treatment. Clinicians may forecast to a good extent if a given patient will respond or not, based on a number of data and sensations that emerge from face to face assessment. Conversely, clinical predictors of non response emerging from literature are largely unsatisfactory. Here we try to fill this gap, suggesting a comprehensive assessment of patients that may overcome the limitation of standardized assessments and detecting the factors that plausibly contribute to so marked differences in depressive disorders outcome. For this aim we present and discuss two clinical cases. Mr. A was an industrial manager who came to psychiatric evaluation with a severe depressive episode. His employment was demanding and the depressive episode undermined his capacity to manage it. Based on standardized assessment, Mr. A condition appeared severe and potentially dramatic. Mrs. B was a housewife who came to psychiatric evaluation with a moderate depressive episode. Literature predictors would suggest Mrs. B state as associated with a more favourable outcome. However the clinician impression was not converging with the standardized assessment and in fact the outcome will reverse the prediction based on the initial formal standard evaluation. Although the present report is based on two clinical cases and no generalizability is possible, a more detailed analysis of personality, temperament, defense mechanisms, self esteem, intelligence and social adjustment may allow to formalize the clinical impressions used by clinicians for biologic and pharmacologic studies.

Serotonergic and non-serotonergic targets in the pharmacotherapy of visceral hypersensitivity

Visceral hypersensitivity is considered a key mechanism in the pathogenesis of functional gastrointestinal (GI) disorders. Targeting visceral hypersensitivity seems an attractive approach to the development of drugs for functional GI disorders. This review summarizes current knowledge on targets for the treatment of visceral hypersensitivity, and the status of current and future drug and probiotic treatment development, and the role of pharmacogenomic factors.

Dysbindin associated with selective serotonin reuptake inhibitor antidepressant efficacy

OBJECTIVE

Antidepressant drug efficacy is partially under genetic control and a number of gene variants have been associated with antidepressants efficacy over the last few years. In the search for further genes influencing antidepressant response we focused on the dysbindin gene (dystrobrevin-binding-protein 1, DTNBP1).

BASIC METHODS

One hundred and four Korean inpatients affected by major depressive disorder were treated with various antidepressants at standard therapeutic daily doses and rated with the 10-items Montgomery-Asberg Depression rating scale (MADRS) at baseline and discharge. Five DTNBP1 variants (rs3213207 A/G, rs1011313 C/T, rs2005976 G/A, rs760761 C/T and rs2619522 A/C) were analysed for all patients.

RESULTS

Rs2005976 was found to be significantly associated with final MADRS scores, with the rarest A allele associated with higher final scores (P=0.00055), rs760761 also showed a significant association (P=0.0058) and rs2619522 showed a positive trend (P=0.025). Markers were not significantly associated with Clinical Global Impression Scale scores. Five marker haplotypes were mildly associated with MADRS final scores but when considering the block composed of the three single nucleotide polymorphisms individually associated with response (rs2005976, rs760761 and rs2619522), results were more marked (P=0.0096), with the more frequent G-C-A haplotype associated with a positive outcome.

CONCLUSIONS

Despite limitations due to the sample size and the mild antidepressant response, we observed a significant association between DTNBP1 variants and antidepressant response.

Pharmacogenomics

So far no pharmacogenetic/genomic study has been conducted specifically for anxiety disorders. Some of the presented results, however, do pertain to such disorders. For example, pharmacokinetic aspects of antidepressant drug therapy likely also apply to patients with anxiety disorders, and several genetic polymorphisms in the cytochrome P450 (CYP) gene family and drug transporter molecules, such as the multidrug resistance (MDR) gene type 1, have been reported to influence the pharmacokinetics of antidepressant drugs. At this stage of pharmacogenomics research, it is difficult to interpret the relevance of pharmacodynamic-genetic association studies conducted in depressed patients for anxiety disorders. A number of studies have reported an influence of polymorphisms of genes mostly in the serotonergic pathway on the response to antidepressant drugs in patients suffering from depression. In order to know whether they can be extrapolated to patients with anxiety disorders, clinical studies are warranted. Despite all the shortcomings of the currently available pharmacogenetic studies, this field holds great promise for the treatment of anxiety disorders. In the future, psychiatrists may be able to base treatment decisions (i.e., the type and dose of prescribed drug) on more objective parameters than only the diagnostic algorithms used now. This will limit unwanted side effects and adverse drug reactions, and could reduce time to response, resulting in a more individualized pharmacotherapy.

Migraine with and without aura: association with depression and anxiety disorder in a population-based study. The HUNT Study

Some data indicate that migraine with aura (MA) is more strongly associated with anxiety disorder and depression than migraine without aura (MoA), but the evidence is not conclusive. In the Nord-Trøndelag Health study 1995-1997, a total of 49 205 (75% of the participants) subjects gave valid answers to both HADS (Hospital Anxiety and Depression Scale) and a validated headache questionnaire. Associations between anxiety disorder/depression and MA/MoA were evaluated by multiple logistic regression analysis. Depression (DEP) [odds ratio (OR) 1.7; 95% confidence interval (CI) 1.2, 2.6] and depression with comorbid anxiety disorder (COM) (OR 1.6; 95% CI 1.2, 2.1) were more likely in women having MA than in those with MoA. No stronger association was found for pure anxiety disorder (ANX) in MA vs. MoA (OR 0.9; 95% CI 0.7, 1.5). Among men, we found no difference in prevalence of depression and anxiety disorders between MA and MoA. This is a new finding that might have relevance for both research and clinical treatment.

Pharmacogenomics and antidepressant drugs

While antidepressant pharmacotherapy is an effective treatment of depression, it still is hampered by a delayed time of onset of clinical improvement and a series of side effects. Moreover, a substantial group of patients has only limited response or fails to respond at all. One source accounting for these variations are genetic differences as currently analysed by single nucleotide polymorphisms (SNP) mapping. In recent years a number of pharmacogenetic studies on antidepressant drugs have been published. So far they mostly focused on metabolizing enzymes of the cytochrome P450 (CYP) families and genes within the monoaminergic system with compelling evidence for an effect of CYP2D6 polymorphisms on antidepressant drug plasma levels and of a serotonin transporter promoter polymorphism on clinical response to a specific class of antidepressants, the selective serotonin reuptake inhibitors. It is clear, however, that other candidate systems have to be considered in the pharmacogenetics of antidepressant drugs, such as neuropeptidergic systems, the hypothalamus-pituitary adrenal (HPA) axis and neurotrophic systems. There is recent evidence that polymorphisms in genes regulating the HPA axis have an important impact on response to antidepressants. These studies mark the beginning of an emerging standard SNP profiling system that ultimately allows identifying the right drug for the right patient at the right time.

The influence of Serotonin Transporter Promoter Polymorphism (SERTPR) and other polymorphisms of the serotonin pathway on the efficacy of antidepressant treatments

The definition of a genetic liability profile for specific antidepressant treatment will soon be available offering considerable help in early detection of effective therapy in affective disorders. The search for genetic factors predisposing to drug response or side-effects in affective disorders started only in the last few years. The efficacy of antidepressant action was associated with several polymorphisms, located on coding genes of proteins thought to be involved in the different mechanisms of action of antidepressant treatments. Among these, gene variants in sequences of serotonin pathway proteins were candidate, both for the well known evidence of its involvement in the development of depressive symptomathology and for the wide-world use of selective serotonin reuptake inhibitors as first choice treatment of depression. A polymorphism in the promoter region of the serotonin transporter (SERTPR) was independently associated with efficacy for a range of treatments, other polymorphism located on the tryptophan hydroxylase gene, 5-HT2a receptor and G-protein beta 3 showed some association, while other candidate genes were not associated with treatment efficacy. Possible liability genes controlling at least to some extent both acute and long-term treatment were identified, and the further objective is to identify other candidate genes in order to define individualized treatments according to genetic profile in a future. The present paper reviews the pharmacogenetic studies published to date, focusing the attention on the serotonergic pathway.

Candidate genes for antidepressant response to selective serotonin reuptake inhibitors

Selective serotonin reuptake inhibitors (SSRIs) can safely and successfully treat major depression, although a substantial number of patients benefit only partially or not at all from treatment. Genetic polymorphisms may play a major role in determining the response to SSRI treatment. Nonetheless, it is likely that efficacy is determined by multiple genes, with individual genetic polymorphisms having a limited effect size. Initial studies have identified the promoter polymorphism in the gene coding for the serotonin reuptake transporter as moderating efficacy for several SSRIs. The goal of this review is to suggest additional plausible polymorphisms that may be involved in antidepressant efficacy. These include genes affecting intracellular transductional cascades; neuronal growth factors; stress-related hormones, such as corticotropin-releasing hormone and glucocorticoid receptors; ion channels and synaptic efficacy; and adaptations of monoaminergic pathways. Association analyses to examine these candidate genes may facilitate identification of patients for targeted alternative therapies. Determining which genes are involved may also assist in identifying future, novel treatments.

Profiles of "manic" symptoms in bipolar I, bipolar II and major depressive disorders

BACKGROUND

Classical authors such as Kraepelin, as well as the emerging literature during the past decade, indicate that manic-like signs and symptoms are present to a variable degree in all mood disorders. Current nosography does not differentiate between them and only the number of symptoms or severity is used for classification. This is particularly true for mania and hypomania. This paper will analyze the patterns of manic symptoms in bipolar I (BP-I), bipolar II (BP-II) and major depressive disorders (MDD), to test the hypothesis that mania and hypomania have different profiles, and ascertain which excitatory manic phenomena do occur in unipolar MDD.

METHODS

Six hundred and fifty-two inpatients (158 BP-I, 122 BP-II and 372 MDD) were assessed using the operational criteria for psychotic illness checklist (OPCRIT) [Arch. Gen. Psychiatry 48 (1991) 764] with a lifetime perspective. Manic or hypomanic symptoms were investigated and compared between BP-I, BP-II and MDD.

RESULTS

When compared with BP-II, BP-I disorder had a higher prevalence of reckless activity, distractibility, psychomotor agitation, irritable mood and increased self-esteem. These five symptoms correctly classified 82.8% of BP-I and 80.1% of BP-II patients. One or two manic symptoms were observed in more than 30% of major depressive patients; psychomotor agitation was the most frequent manifestations present in 18% of the MDD group.

LIMITATIONS

We did not control for severity of symptoms, nor for neuroleptic use that could produce akathisia.

CONCLUSIONS

This study suggests that mania and hypomania can be differentiated in their symptom profiles, and highlights the presence of few manic symptoms, particularly psychomotor agitation, in MDD. From the standpoint of number of manic signs and symptoms, controlling for psychomotor agitation did not substantially change the predictive power of the remaining manic symptoms. Given that excitatory manic signs and symptoms are present to a decreasing degree in BP-I, BP-II and MDD, these disorders can be proposed to lie along a dimensional model. Overall, these data are compatible with the concept of a bipolar spectrum, whereby each of the affective subtypes requires specific genetic factors.

Further evidence of a combined effect of SERTPR and TPH on SSRIs response in mood disorders

We reported an independent association of the short variant of the serotonin transporter gene-linked polymorphic region (SERTPR) and tryptophan hydroxylase (TPH) genes with antidepressant response to selective serotonin reuptake inhibitors (SSRIs). The aim of the present study was to confirm the effect of the SERTPR and TPH gene variants on the SSRIs antidepressant activity in a new sample of major and bipolar depressives. Two hundred and twenty one inpatients (major depressives = 128, bipolar disorder = 93) were treated with SSRIs (fluvoxamine or paroxetine) for 6 weeks; the severity of depressive symptoms was weekly assessed with the Hamilton Rating Scale for Depression (HAMD). SERTPR and TPH variants were determined using PCR-based techniques, 220 subjects genotyped for SERTPR and 221 for TPH that were never included in previous studies. SERTPR*s/s variant association with a poor response to SSRI treatment was confirmed, even if with less significant P values (P = 0.034), independently from clinical variables; pooling the present sample with previous ones we observed a highly significant effect (P < 0.000001). TPH*A/A variants showed higher HAMD scores throughout the trial but with only a trend in the same direction of our previous study in terms of a worse response of A/A genotypes. Thus, the previous positive association was not fully replicated for TPH. The present independent replication confirms SERTPR variants as a liability factor for antidepressant efficacy while the TPH effect is not unequivocal.

Pharmacogenetics and bipolar disorder

Bipolar disorder (BD) is a major psychiatric condition that commonly requires prophylactic and episodic treatment. There is important variability in the therapeutic response and side-effect profiles to currently available pharmacological agents. Pharmacogenetics have provided new hopes to develop more efficient treatment strategies tailored to the individual patient's needs. This review assesses nonsystematically studies using pharmacogenetic strategies in BD. Most of these studies have focused on patients selected according to lithium response, and more recently, a growing number of studies have been investigating genetic factors in mixed samples of patients classified according to response to antidepressant treatment. Although previous clinical and family studies support the use of pharmacogenetic strategies both to increase phenotype homogeneity as well as to identify genetic factors that may mediate response to treatment, most molecular studies carried out to date are still preliminary and in need of external validation. A major problem has been comparability between studies, in part, because of differences in the criteria used to define response. More attention should be paid to standardize the criteria for drug response definition.

Long-term responsiveness to lithium as a pharmacogenetic outcome variable: treatment and etiologic implications

The importance of genes in the etiology of bipolar disorder has been substantiated through family, twin, and adoption studies. Bipolar disorder is treated at the prophylactic and episodic levels; lithium is one of the most common forms of prophylactic treatment. Recently, pharmacogenetics has come to play an active role in the elucidation of genetic factors that may play a role in modulating lithium response. This strategy has provided hope for advancements in understanding the genetics of lithium-responsive bipolar disorder. This review encompasses studies that have used populations of lithium responders and non-responders to carry out family, linkage, or association studies, as well as some insight into possible mechanisms by which lithium produces its prophylactic effect. Although data examining the pharmacogenetics of bipolar disorder remain scarce, this is a promising avenue of investigation to help genetically define more homogeneous populations or to search for genetic predictors of drug response.

Clinical and demographic features of mood disorder subtypes

The aim of this study was to investigate demographic, clinical and symptomatologic features of the following mood disorder subtypes: bipolar disorder I (BP-I); bipolar disorder II (BP-II); major depressive disorder, recurrent (MDR); and major depressive episode, single episode (MDSE). A total of 1832 patients with mood disorders (BP-I=863, BP-II=141, MDR=708, and MDSE=120) were included in our study. The patients were assessed using structured diagnostic interviews and the operational criteria for psychotic illness checklist (n=885), the Hamilton depression rating scale (n=167), and the social adjustment scale (n=305). The BP-I patients were younger; had more hospital admissions; presented a more severe form of symptomatology in terms of psychotic symptoms, disorganization, and atypical features; and showed less insight into their disorder than patients in the other groups. Compared with the major depressive subgroups, BP-I patients were more likely to have an earlier age at onset, an earlier first lifetime psychiatric treatment, and a greater number of illness episodes. BP-II patients had a higher suicide risk than both BP-I and MDSE patients. MDSE patients presented less severe symptomatology, lower age at observation, and a higher number of males. The retrospective approach and the selection constraints due to the inclusion criteria are the main limitations of the study. Our data support the view that BP-I disorder is quite different from the remaining mood disorders from a demographic and clinical perspective, with BP-II disorder having an intermediate position to MDR and MDSE, that is, as a less severe disorder. This finding may help in the search for the biological basis of mood disorders.

Pharmacogenetics of bipolar disorder

To review the pharmacogenetics of bipolar disorders, the authors searched databases for genetic association and linkage studies involving response to long-term prophylactic lithium treatment, as well as treatment with antidepressants or clozapine. Significant ethnic variations in the metabolism and efficacy of antidepressants, as well as clozapine, have been reported by several groups. Systematic studies suggest that that genetic factors affect the response to prophylactic lithium treatment. Numerous associations between the three traits of interest and candidate gene polymorphisms have been proposed. Among these, an association between the serotonin transporter gene and response to serotonin reuptake inhibitors appears robust. Considerable interest has also focused on serotonergic gene polymorphisms and response to clozapine. Response to pharmacotherapy in bipolar disorders may be mediated by genetic factors, but the role played by heritability is unknown.

Pharmacogenetics in affective disorders

Pharmacogenetics will be of substantial help in the field of affective disorders pharmacotherapy. The possible definition of a genetic liability profile for drug side-effects and efficacy will be of great help in treatments that need weeks to months to be effective. During the last few years, a number of groups have reported possible liability genes. The efficacy and time of onset of selective serotonin reuptake inhibitors have been associated with a polymorphism in the promoter region of the transporter (SERTPR) in many independent studies, while variants at the tryptophan hydroxylase gene, 5-HT2a receptor and G-protein beta3 have been associated with them in pilot studies. Lithium long-term prophylactic efficacy has been associated with SERTPR, TPH and inositol polyphosphate 1-phosphatase variants, though in unreplicated samples. A number of further candidate genes were not associated with these treatments. In conclusion, both acute and long-term treatments appear to be, at least to some extent, under genetic influence and preliminary data have identified possible liability genes.

Genetic factors and treatment of mood disorders

OBJECTIVES

This paper reviews the pharmacogenetics of mood disorders.

METHODS

We have searched the literature for published studies and abstracts relevant for genetic effects in acute antidepressant treatment and in long-term prophylactic treatment.

RESULTS

The most promising findings to date show an association of the serotonin transporter (5-HTT) gene and the response to serotonin reuptake inhibitors. Genetic factors also appear to play a significant role in the outcome of long-term lithium treatment. The phenotype of lithium-responsive bipolar disorder is associated with stronger genetic effects as well as with an increased phenotypic homogeneity.

CONCLUSIONS

Genetic factors likely influence treatment response in mood disorders. Clarifying their precise role will have implications for treatment as well as for understanding the pathophysiological mechanisms of these disorders.

Tryptophan hydroxylase gene associated with paroxetine antidepressant activity

The possible association of the A218C tryptophan hydroxylase (TPH) gene variant with the antidepressant activity of paroxetine was investigated in a sample of 121 inpatients affected by a major depressive episode and treated with paroxetine 20-40 mg with either placebo or pindolol in a double blind design for 4 weeks. The severity of depressive symptoms was weekly assessed with the Hamilton Rating Scale for Depression. TPH allelic variants were determined in each subject using a PCR-based technique. TPH*A/A and TPH*A/C variants were associated with a poorer response to paroxetine treatment when compared to TPH*C/C (P=0.005); this difference was not present in the pindolol augmented group. Other variables, such as sex, diagnosis, presence of psychotic features, severity of depressive symptomatology at baseline and paroxetine plasma level, were not associated with the outcome. TPH gene variants are therefore a possible modulator of paroxetine antidepressant activity.

Influence of tryptophan hydroxylase and serotonin transporter genes on fluvoxamine antidepressant activity

The aim of the present study was to test a possible effect of the A218C tryptophan hydroxylase (TPH) gene variant on the antidepressant activity of fluvoxamine in a sample of major and bipolar depressives, with or without psychotic features. Two hundred and seventeen inpatients were treated with fluvoxamine 300 mg and either placebo or pindolol in a double blind design for 6 weeks. The severity of depressive symptoms was weekly assessed with the Hamilton Rating Scale for Depression. TPH allelic variants were determined in each subject by using a PCR-based technique. No significant finding was observed in the overall sample as well as in the pindolol group, while TPH*A/A was associated with a slower response to fluvoxamine treatment in subjects not taking pindolol (P = 0.001). This effect was independent from the previously reported influence of 5-HTTLPR polymorphism. If confirmed, these results may shed further light on the genetically determined component of the response to pharmacological treatments, thus helping the clinician to individualize each patient's therapy according to their genetic pattern.

Factors affecting fluvoxamine antidepressant activity: influence of pindolol and 5-HTTLPR in delusional and nondelusional depression

BACKGROUND

It has been recently reported that the short variant of the serotonin transporter (5-HTT) gene-linked functional polymorphic region (5-HTTLPR) influences the antidepressant response to certain selective serotonin reuptake inhibitors. The aim of the present study was to test this finding in a sample of major and bipolar depressives, with or without psychotic features.

METHODS

One hundred fifty-five inpatients were treated with fluvoxamine 300 mg and either placebo or pindolol in a double-blind design for 6 weeks. The severity of depressive symptoms was weekly assessed with the Hamilton Rating Scale for Depression. Allelic variation of 5-HTTLPR in each subject was determined using a polymerase chain reaction-based technique.

RESULTS

5-HTTLPR short variant was associated with a poor response to fluvoxamine treatment, independently from the recorded clinical variables. More specifically, the diagnosis, the presence of psychotic features, and the severity of depressive symptomatology did not influence this association. Conversely, pindolol augmentation may ameliorate the rate of response in 5-HTTLPR short variant subjects, thus reducing the difference in the response rate among the genotype variants.

CONCLUSIONS

If confirmed, these results may improve patient care by helping the clinician to individualize treatment according to the patient's genetic 5-HTTLPR pattern.

Transtorno bipolar

Os resultados de estudos de famílias sugerem que o transtorno bipolar tenha uma base genética. Essa hipótese foi reforçada em estudos de adoção e de gêmeos. A herança do transtorno bipolar é complexa, envolve vários genes, além de apresentar heterogeneidade e interação entre fatores genéticos e não-genéticos. Achados, que já foram replicados, já implicaram os cromossomos 4, 12, 18 e 21, entre outros, na busca por genes de suscetibilidade. Os resultados mais promissores foram obtidos através de estudos de ligação. Por outro lado, os estudos de associação geraram dados interessantes, mas ainda vagos. Os estudos de populações de pacientes homogêneos e a melhor definição do fenótipo deverão contribuir para avanços futuros. A identificação dos genes relacionados ao transtorno bipolar irá permitir o melhor entendimento e tratamento dessa doença.