Population frequencies of the Triallelic 5HTTLPR in six Ethnicially diverse samples from North America, Southeast Asia, and Africa

The Value of Pharmacogenomics for White and Indigenous Americans after Kidney Transplantation

BACKGROUND

There is a paucity of evidence to inform the value of pharmacogenomic (PGx) results in patients after kidney transplant and how these results differ between Indigenous Americans and Whites. This study aims to identify the frequency of recommended medication changes based on PGx results and compare the pharmacogenomic (PGx) results and patients' perceptions of the findings between a cohort of Indigenous American and White kidney transplant recipients.

METHODS

Thirty-one Indigenous Americans and fifty White kidney transplant recipients were studied prospectively. Genetic variants were identified using the OneOme RightMed PGx test of 27 genes. PGx pharmacist generated a report of the genetic variation and recommended changes. Pre- and post-qualitative patient surveys were obtained.

RESULTS

White and Indigenous American subjects had a similar mean number of medications at the time of PGx testing (mean 13 (SD 4.5)). In the entire cohort, 53% received beta blockers, 30% received antidepressants, 16% anticoagulation, 47% pain medication, and 25% statin therapy. Drug-gene interactions that warranted a clinical action were present in 21.5% of patients. In 12.7%, monitoring was recommended. Compared to the Whites, the Indigenous American patients had more normal CYP2C19 (p = 0.012) and CYP2D6 (p = 0.012) activities. The Indigenous American patients had more normal CYP4F2 (p = 0.004) and lower VKORC (p = 0.041) activities, phenotypes for warfarin drug dosing, and efficacy compared to the Whites. SLC6A4, which affects antidepressant metabolism, showed statistical differences between the two cohorts (p = 0.017); specifically, SLC6A4 had reduced expression in 45% of the Indigenous American patients compared to 20% of the White patients. There was no significant difference in patient perception before and after PGx.

CONCLUSIONS

Kidney transplant recipients had several drug-gene interactions that were clinically actionable; over one-third of patients were likely to benefit from changes in medications or drug doses based on the PGx results. The Indigenous American patients differed in the expression of drug-metabolizing enzymes and drug transporters from the White patients.

Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2D6, CYP2C19, CYP2B6, SLC6A4, and HTR2A Genotypes and Serotonin Reuptake Inhibitor Antidepressants

Serotonin reuptake inhibitor antidepressants, including selective serotonin reuptake inhibitors (SSRIs; i.e., citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline), serotonin and norepinephrine reuptake inhibitors (i.e., desvenlafaxine, duloxetine, levomilnacipran, milnacipran, and venlafaxine), and serotonin modulators with SSRI-like properties (i.e., vilazodone and vortioxetine) are primary pharmacologic treatments for major depressive and anxiety disorders. Genetic variation in CYP2D6, CYP2C19, and CYP2B6 influences the metabolism of many of these antidepressants, which may potentially affect dosing, efficacy, and tolerability. In addition, the pharmacodynamic genes SLC6A4 (serotonin transporter) and HTR2A (serotonin-2A receptor) have been examined in relation to efficacy and side effect profiles of these drugs. This guideline updates and expands the 2015 Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for CYP2D6 and CYP2C19 genotypes and SSRI dosing and summarizes the impact of CYP2D6, CYP2C19, CYP2B6, SLC6A4, and HTR2A genotypes on antidepressant dosing, efficacy, and tolerability. We provide recommendations for using CYP2D6, CYP2C19, and CYP2B6 genotype results to help inform prescribing these antidepressants and describe the existing data for SLC6A4 and HTR2A, which do not support their clinical use in antidepressant prescribing.

Effects of Pharmacogenomic Testing in Clinical Pain Management: Retrospective Study

BACKGROUND

The availability of pharmacogenomic (PGx) methods to determine the right drug and dosage for individualized patient treatment has increased over the past decade. Adoption of the resulting PGx reports in a clinical setting and monitoring of clinical outcomes is a challenging and long-term commitment.

OBJECTIVE

This study summarizes an extended PGx deep sequencing panel intended for medication dosing and prescription guidance newly adopted in a pain management clinic. The primary outcome of this retrospective study reports the number of cases and types of drugs covered, for which PGx data appears to have assisted in optimal drug prescription and dosing.

METHODS

A PGx panel is described, encompassing 23 genes and 141 single-nucleotide polymorphisms or indels, combined with PGx dosing guidance and drug-gene interaction (DGI) and drug-drug interaction (DDI) reporting to prevent adverse drug reactions (ADRs). During a 2-year period, patients (N=171) were monitored in a pain management clinic. Urine toxicology, PGx reports, and progress notes were studied retrospectively for changes in prescription regimens before and after the PGx report was made available to the provider. An additional algorithm provided DGIs and DDIs to prevent ADRs.

RESULTS

Among patient PGx reports with medication lists provided (n=146), 57.5% (n=84) showed one or more moderate and 5.5% (n=8) at least one serious PGx interaction. A total of 96 (65.8%) patients showed at least one moderate and 15.1% (n=22) one or more serious DGIs or DDIs. A significant number of active changes in prescriptions based on the 102 PGx/DGI/DDI report results provided was observed for 85 (83.3%) patients for which a specific drug was either discontinued or switched within the defined drug classes of the report, or a new drug was added.

CONCLUSIONS

Preventative action was observed for all serious interactions, and only moderate interactions were tolerated for the lack of other alternatives. This study demonstrates the application of an extended PGx panel combined with a customized informational report to prevent ADRs and improve patient care.

Serotonin Transporter Gene Polymorphisms and Maternal Overprotection Regulate Adult Social Expectations on Close Relationships

Humans are evolutionary-driven to adult mating and conceive social expectations on the quality of their affiliations. The genetic susceptibility to adverse environments in critical periods can alter close relationships. The current research investigates how the promoter region of the Serotonin Transporter Gene (5-HTTLPR) and perceived caregiving behavior in childhood could influence the social expectations on close adult relationships. For this purpose, 5-HTTLPR data was collected from the buccal mucosa of 65 Italian individuals (33 males). The participants filled (a) the Parental Bonding Instrument (PBI) to provide the levels of care and overprotection from mother and father, and (b) the Experience in Close Relationships-Revised (ECR-R) to report the social expectations on the intimate relationship assessed in terms of anxiety and avoidance from the partner. An interaction effect between 5-HTTLPR and PBI dimensions on the ECR-R scores was hypothesized. Results confirmed that the interplay between the genetic groups and history of maternal overprotection predicted avoidance experienced in romantic relationships in adulthood. Moreover, both adult anxiety and avoidance felt in an intimate relationship were found to covary as a function of maternal overprotection. The present work proposes further evidence of the genetic and parental mechanisms regulating social expectations involved in close relationships.

Identification and functional characterization of the extremely long allele of the serotonin transporter-linked polymorphic region

SLC6A4, which encodes the serotonin transporter, has a functional polymorphism called the serotonin transporter-linked polymorphic region (5-HTTLPR). The 5-HTTLPR consists of short (S) and long (L) alleles, each of which has 14 or 16 tandem repeats. In addition, the extralong (XL) and other rare alleles have been reported in 5-HTTLPR. Although they are more frequent in Asian and African than in other populations, the extent of variations and allele frequencies (AFs) were not addressed in a large population. Here, we report the AFs of the rare alleles in a large number of Japanese subjects (N = 2894) consisting of two cohorts. The first cohort (case-control study set, CCSS) consisted of 1366 subjects, including 485 controls and 881 patients with psychosis (bipolar disorder or schizophrenia). The second cohort (the Arao cohort study set, ACSS) consisted of 1528 elderly subjects. During genotyping, we identified 11 novel 5-HTTLPR alleles, including 3 XL alleles. One novel allele had the longest subunit ever reported, consisting of 28 tandem repeats. We named this XL_28-A. An in vitro luciferase assay revealed that XL_28-A has no transcriptional activity. XL_28-A was found in two unrelated patients with bipolar disorder in the CCSS and one healthy subject in the ACSS who did not show depressive symptoms or a decline in cognitive function. Therefore, it is unlikely that XL_28-A is associated with psychiatric disorders, despite its apparent functional deficit. Our results suggest that unraveling the complex genetic variations of 5-HTTLPR will be important for further understanding its role in psychiatric disorders.

Lack of association of common polymorphisms linked to empathic behavior with self-reported trait empathy in healthy volunteers

BACKGROUND

In a previously specified sample of 421 healthy subjects, we found associations of a common oxytocin receptor (OXTR) polymorphism with self-reported trait empathy. In this study, we used this sample to explore polymorphisms in other genes which have been frequently linked to empathic behavior for associations with self-reported trait empathy: CD38 (CD38), involved in oxytocin secretion, the serotonin transporter (SLC6A4), the Catechol-O-Methyltransferase (COMT) and the corticotropin releasing hormone receptor 1 (CRHR1).

METHODS

We genotyped our sample for the following common polymorphisms: rs3796863 in the CD38 gene, 5-HTTLPR in the SLC6A4 gene, rs4680 in the COMT gene and rs242924 in the CRHR1 gene. Dispositional empathy was tested using Davis' Interpersonal Reactivity Index (IRI). We used a Bonferroni corrected alpha level of p = 0.002 to adjust for multiple comparisons.

RESULTS

None of the genotypes were associated with any of the IRI scales for the complete sample (n = 421) or for the sub-groups of male (n = 213) and female (n = 190) participants. Our sample of 421 participants achieved 95% power to detect effects greater than r = ±0.18. For smaller effects, however, false negatives could not be rejected with equal confidence as false positives.

CONCLUSIONS

We conclude that an association between the four polymorphisms with trait empathy measured by the IRI may not be present. We propose that the associations that have been found in other studies can be largely explained by differences in empathy-related constructs and measurements.

The 5-HTTLPR polymorphism impacts moral permissibility of impersonal harmful behaviors

Inspired by the roles of serotonin in an emotional aversion to harmful actions, we examined to what extent serotonin transporter gene (5-HTT)–linked polymorphic region (5-HTTLPR), a proxy for measuring serotonin function, underpinned the individual differences in moral judgment through cross-sectional analysis and two-wave comparison. The cross-sectional analysis with a larger cohort (N = 1197) showed that the SS carriers of the 5-HTTLPR polymorphism, corresponding to the low ratio of serotonin recycling from the synaptic cleft, rated impersonal harmful actions (e.g. flipping a switch to divert a train to hit one person instead of five people) as more permissible as compared with the L-allele carriers. The two-wave comparison with a subsample from the larger cohort (N = 563) indicated that the association between 5-HTTLPR polymorphism and moral permissibility of impersonal harmful actions was stable from wave 1 to wave 2. Thus, these findings highlight the importance of the 5-HTTLPR polymorphism to harmful moral behaviors.

SERT and BDNF polymorphisms interplay on neuroticism in borderline personality disorder

Objective

Genetic factors underlying different personality traits are not entirely understood, particularly how genes interact to modulate their effect. We studied 76 patients diagnosed with borderline personality disorder (BPD), characterized by extreme levels of personality traits, especially neuroticism (N), in which we genotyped two polymorphisms, the 5HTTLPR of the Serotonin transporter (SERT) gene, and the Val66Met of the Brain-derived neurotrophic factor (BDNF) gene.

Results

We found an association with SERT, where S-allele carriers had significantly higher levels of N than L-homozygous. Furthermore, we found that the protective effect of L-homozygosity is only evident on A-allele carriers of the BDNF Val66Met polymorphism. Genetic constitution in SERT and BDNF seems to be important in neuroticism, the most relevant personality trait on BPD.

In Search of Reward Deficiency Syndrome (RDS)-free Controls: The "Holy Grail" in Genetic Addiction Risk Testing

BACKGROUND

The search for an accurate, gene-based test to identify heritable risk factors for Reward Deficiency Syndrome (RDS) was conducted based on hundreds of published studies about the role of dopamine in addictive behaviors, including risk for drug dependence and compulsive/impulsive behavior disorders. The term RDS was first coined by Blum's group in 1995 to identify a group of behaviors with a common neurobiological mechanism associated with a polymorphic allelic propensity for hypodopaminergia.

OBJECTIVES

To outline the process used to select risk alleles of reward genes for the Genetic Addiction Risk Score (GARS) test. Consequently, to address the limitations caused by inconsistent results that occur in many case-control behavioral association studies. These limitations are perhaps due to the failure of investigators to adequately screen controls for drug and alcohol use disorder, and any of the many RDS behaviors, including nicotine dependence, obesity, pathological gambling, and internet gaming addiction.

METHODS

Review of the literature related to the function of risk alleles of reward genes associated with hypodopaminergia relevant case-control association studies for the selection of alleles to be measured by the Genetic Addiction Risk Score (GARS) test.

RESULTS

The prevalence of the DRD2 A1 allele in unscreened controls (33.3%), compared to "Super-Controls" [highly screened RDS controls (3.3%) in proband and family] is used to exemplify a possible solution.

CONCLUSION

Unlike one gene-one disease (OGOD), RDS is polygenetic, and very complex. In addition, any RDS-related behaviors must be eliminated from the control group in order to obtain the best possible statistical analysis instead of comparing the phenotype with disease-ridden controls.

Mental health is biological health: Why tackling "diseases of the mind" is an imperative for biological anthropology in the 21st century

The germ theory of disease and the attendant public health initiatives, including sanitation, vaccination, and antibiotic treatment, led to dramatic increases in global life expectancy. As the prevalence of infectious disease declines, mental disorders are emerging as major contributors to the global burden of disease. Scientists understand little about the etiology of mental disorders, however, and many of the most popular psychopharmacological treatments, such as antidepressants and antipsychotics, have only moderate-to-weak efficacy in treating symptoms and fail to target biological systems that correspond to discrete psychiatric syndromes. Consequently, despite dramatic increases in the treatment of some mental disorders, there has been no decrease in the prevalence of most mental disorders since accurate record keeping began. Many researchers and theorists are therefore endeavoring to rethink psychiatry from the ground-up. Anthropology, especially biological anthropology, can offer critical theoretical and empirical insights to combat mental illness globally. Biological anthropologists are unique in that we take a panhuman approach to human health and behavior and are trained to address each of Tinbergen's four levels of analysis as well as culture. The field is thus exceptionally well-situated to help resolve the mysteries of mental illness by integrating biological, evolutionary, and sociocultural perspectives.

Adaptive developmental plasticity in rhesus macaques: the serotonin transporter gene interacts with maternal care to affect juvenile social behaviour

Research has increasingly highlighted the role that developmental plasticity-the ability of a particular genotype to produce variable phenotypes in response to different early environments-plays as an adaptive mechanism. One of the most widely studied genetic contributors to developmental plasticity in humans and rhesus macaques is a serotonin transporter gene-linked polymorphic region (5-HTTLPR), which determines transcriptional efficiency of the serotonin transporter gene in vitro and modifies the availability of synaptic serotonin in these species. A majority of studies to date have shown that carriers of a loss-of-function variant of the 5-HTTLPR, the short (s) allele, develop a stress-reactive phenotype in response to adverse early environments compared with long (l) allele homozygotes, leading to the prevalent conceptualization of the s-allele as a vulnerability allele. However, this framework fails to address the independent evolution of these loss-of-function mutations in both humans and macaques as well as the high population prevalence of s-alleles in both species. Here we show in free-ranging rhesus macaques that s-allele carriers benefit more from supportive early social environments than l-allele homozygotes, such that s-allele carriers which receive higher levels of maternal protection during infancy demonstrate greater social competence later in life. These findings provide, to our knowledge, the first empirical support for the assertion that the s-allele grants high undirected biological sensitivity to context in primates and suggest a mechanism through which the 5-HTTLPR s-allele is maintained in primate populations.

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

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

Genetics of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) has been seen to run in families and genetics help to understand its heritability. In this review, we summarize older studies which focused on establishing the familial nature of OCD, including its various dimensions of symptoms, and we focus on recent findings from studies using both the candidate gene approach and genome-wide association study (GWAS) approach. The family studies and twin studies establish the heritability of OCD. Candidate gene approaches have implicated genes in the serotonergic, glutamatergic, and dopaminergic pathways. GWAS has not produced significant results possibly due to the small sample size. Newer techniques such as gene expression studies in brain tissue, stem cell technology, and epigenetic studies may shed more light on the complex genetic basis of OCD.

DRD4 interacts with adverse life events in predicting maternal sensitivity via emotion regulation

We examined whether and how the dopamine receptor D4 (DRD4) interacts with adverse life events to predict maternal sensitivity directly and indirectly via emotion regulation. The sample included 209 (106 European American, 103 African American) mothers and their children (52% female). Sensitive maternal behavior was rated and aggregated across five stress-free and stress-inducing tasks when children were about 2 years old, when mothers also retrospectively reported on their adverse life experiences and transitions throughout childhood from birth to age 20. When children were about 1 year old, mothers reported on their difficulties with emotion regulation. Results from path analysis indicated that mothers who carried the long allele of DRD4 and experienced more adverse life events were less sensitive in interactions with their children. These mothers were also more likely to have difficulties with emotion regulation, which in turn predicted lower maternal sensitivity. These effects were significant above and beyond the effects of maternal education, coherence of mind, race, or infants' DRD4 genotype, and did not vary for African American and European American mothers. Results suggest that genetic predispositions modify the effects of maternal experience of adverse life events on maternal sensitivity and that emotion regulation serves as one mechanism by which genetic factors and gene-environment interactions affect maternal behavior. (PsycINFO Database Record

Serotonin transporter gene polymorphism as a predictor of short-term risk of suicide reattempts

Objective:

The serotonin-transporter-linked polymorphic region (5-HTTLPR) polymorphisms are associated with suicidal behavior; however, prospective studies are scarce. Herein we aim to determine if 5-HTTLPR polymorphisms predict risk of short-term suicide reattempt in a high-risk suicidal sample. We also explore possible mediators or moderators of this relationship.

Methods:

A multicenter prospective cohort study was designed to compare data obtained form 136 patients admitted to the emergency department for current suicidal ideation or a recent suicide attempt. Subjects were clinically evaluated, genotyped, and monitored for a new suicide attempt for 6 months.

Results:

At 6 months of follow up, 21% of the subjects had a new suicide attempt. The frequency of L-allele and L-carrier was higher in reattempters when compared with non-reattempters (55.8% vs. 35.4%, p = 0.01 and 76.9% vs. 54.2%, p = 0.04, respectively). Reattempters also differ from non-reattempters patients with respect to age, history of previous suicide attempts, and age of onset of suicidal behavior. The logistic regression model showed that L-carriers had an odds ratio of 2.8 (95% CI: 1.0–7.6) for reattempts when compared to SS genotype. The adjusted model indicates that this association is not mediated or moderated by impulsivity.

Conclusion:

The 5-HTTLPR polymorphisms predicted short-term risk of suicidal reattempt independently of age and sex. L-carriers have almost three times more risk of relapse when compared with SS carriers.

Depressive mood ratings are reduced by MDMA in female polydrug ecstasy users homozygous for the l-allele of the serotonin transporter

MDMA exerts its main effects via the serotonergic system and the serotonin transporter. The gene coding for this transporter determines the expression rate of the transporter. Previously it was shown that healthy individuals with the short allelic variant ('s-group') of the 5-HTTLPR-polymorphism displayed more anxiety and negative mood, and had a lower transcriptional efficiency compared to individuals who are homozygous for the l-allele ('l-group'). The present study aimed to investigate the role of the 5-HTTLPR polymorphism in MDMA-induced mood effects. Four placebo-controlled, within-subject studies were pooled, including in total 63 polydrug ecstasy users (N_s-group = 48; N_l-group = 15) receiving MDMA 75 mg and placebo on two test days, separated by minimally 7 days. Mood was assessed by means of the Profile of Mood States. Findings showed that MDMA induced -independent of sex- a positive mood state, and as a side effect also increased two negative affect states, anxiety and confusion. Anxiety ratings were higher in the l-group and independent of treatment or sex. Depression ratings were lowered by MDMA in the female l-group. Findings indicate that the MDMA-induced reduction in self-rated depressive feelings is sex- and genotype-dependent, with females homozygous for the l-allele showing this beneficial effect.

Imaging genetics in neurodevelopmental psychopathology

Neurodevelopmental disorders are defined by highly heritable problems during development and brain growth. Attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), and intellectual disability (ID) are frequent neurodevelopmental disorders, with common comorbidity among them. Imaging genetics studies on the role of disease-linked genetic variants on brain structure and function have been performed to unravel the etiology of these disorders. Here, we reviewed imaging genetics literature on these disorders attempting to understand the mechanisms of individual disorders and their clinical overlap. For ADHD and ASD, we selected replicated candidate genes implicated through common genetic variants. For ID, which is mainly caused by rare variants, we included genes for relatively frequent forms of ID occurring comorbid with ADHD or ASD. We reviewed case-control studies and studies of risk variants in healthy individuals. Imaging genetics studies for ADHD were retrieved for SLC6A3/DAT1, DRD2, DRD4, NOS1, and SLC6A4/5HTT. For ASD, studies on CNTNAP2, MET, OXTR, and SLC6A4/5HTT were found. For ID, we reviewed the genes FMR1, TSC1 and TSC2, NF1, and MECP2. Alterations in brain volume, activity, and connectivity were observed. Several findings were consistent across studies, implicating, for example, SLC6A4/5HTT in brain activation and functional connectivity related to emotion regulation. However, many studies had small sample sizes, and hypothesis-based, brain region-specific studies were common. Results from available studies confirm that imaging genetics can provide insight into the link between genes, disease-related behavior, and the brain. However, the field is still in its early stages, and conclusions about shared mechanisms cannot yet be drawn.

Heightened amygdala responsiveness in s-carriers of 5-HTTLPR genetic polymorphism reflects enhanced cortical rather than subcortical inputs: An MEG study

Short allele carriers (S-carriers) of the serotonin transporter gene (5-HTTLPR) show an elevated amygdala response to emotional stimuli relative to long allele carriers (LL-homozygous). However, whether this reflects increased responsiveness of the amygdala generally or interactions between the amygdala and the specific input systems remains unknown. It is argued that the amygdala receives input via a quick subcortical and a slower cortical pathway. If the elevated amygdala response in S-carriers reflects generally increased amygdala responding, then group differences in amygdala should be seen across the amygdala response time course. However, if the difference is a secondary consequence of enhanced amygdala-cortical interactions, then group differences might only be present later in the amygdala response. Using magnetoencephalography (MEG), we found an enhanced amygdala response to fearful expressions starting 40-50 ms poststimulus. However, group differences in the amygdala were only seen 190-200 ms poststimulus, preceded by increased superior temporal sulcus (STS) responses in S-carriers from 130 to 140 ms poststimulus. An enhanced amygdala response to angry expressions started 260-270 ms poststimulus with group differences in the amygdala starting at 160-170 ms poststimulus onset, preceded by increased STS responses in S-carriers from 150 to 160 ms poststimulus. These suggest that enhanced amygdala responses in S-carriers might reflect enhanced STS-amygdala connectivity in S-carriers. Hum Brain Mapp 38:4313-4321, 2017. © 2017 Wiley Periodicals, Inc.

The Serotonin Transporter and Early Life Stress: Translational Perspectives

The interaction between the serotonin transporter (SERT) linked polymorphic region (5-HTTLPR) and adverse early life stressing (ELS) events is associated with enhanced stress susceptibility and risk to develop mental disorders like major depression, anxiety, and aggressiveness. In particular, human short allele carriers are at increased risk. This 5-HTTLPR polymorphism is absent in the rodent SERT gene, but heterozygous SERT knockout rodents (SERT^+/−) show several similarities to the human S-allele carrier, therefore creating an animal model of the human situation. Many rodent studies investigated ELS interactions in SERT knockout rodents combined with ELS. However, underlying neuromolecular mechanisms of the (mal)adaptive responses to adversity displayed by SERT rodents remain to be elucidated. Here, we provide a comprehensive review including studies describing mechanisms underlying SERT variation × ELS interactions in rodents. Alterations at the level of translation and transcription but also epigenetic alterations considerably contribute to underlying mechanisms of SERT variation × ELS interactions. In particular, SERT^+/− rodents exposed to adverse early rearing environment may be of high translational and predictive value to the more stress sensitive human short-allele carrier, considering the similarity in neurochemical alterations. Therefore, SERT^+/− rodents are highly relevant in research that aims to unravel the complex psychopathology of mental disorders. So far, most studies fail to show solid evidence for increased vulnerability to develop affective-like behavior after ELS in SERT^+/− rodents. Several reasons may underlie these failures, e.g., (1) stressors used might not be optimal or severe enough to induce maladaptations, (2) effects in females are not sufficiently studied, and (3) few studies include both behavioral manifestations and molecular correlates of ELS-induced effects in SERT^+/− rodents. Of course, one should not exclude the (although unlikely) possibility of SERT^+/− rodents not being sensitive to ELS. In conclusion, future studies addressing ELS-induced effects in the SERT^+/− rodents should extensively study both long-term behavioral and (epi)genetic aspects in both sexes. Finally, further research is warranted using more severe stressors in animal models. From there on, we should be able to draw solid conclusions whether the SERT^+/− exposed to ELS is a suitable translational animal model for studying 5-HTTLPR polymorphism and stress interactions.

Effects of the serotonin transporter gene, sensitivity of response to alcohol, and parental monitoring on risk for problem alcohol use

The serotonin transporter-linked polymorphic region (5-HTTLPR) of the serotonin transporter gene (SLC6A4) has been previously associated with alcohol-related risk. Most findings point to short (S) allele carriers being at increased risk for negative alcohol outcomes relative to long allele homozygotes, although some work indicates a more complex relationship. The current prospective study aimed to clarify how and under what circumstances variations in 5-HTTLPR transmit risk for various alcohol-related outcomes. Participants were 218 adolescents and young adults (29% female) enrolled in the Michigan Longitudinal Study. We tested a moderated mediation model with 5-HTTLPR as the predictor, Self-Rating of the Effects of Alcohol (SRE) score as the mediator, alcohol-related outcomes as the dependent variables, parental monitoring as the moderator of the SRE to alcohol outcomes path, and prior drinks, sex, age, and body mass index as covariates. Four alcohol-related outcomes were tested. The S allele was associated with higher SRE scores (i.e., lower response to alcohol). Parental monitoring was a significant moderator: At low levels of parental monitoring, higher SRE scores predicted more drinks consumed and binge drinking episodes. At high levels of monitoring, higher SRE scores were significantly related to fewer alcohol-related problems. Findings suggest that one mechanism by which 5-HTTLPR variation transmits alcohol-related risk is through level of response to alcohol. Furthermore, the strength and direction of this effect varied by level of parental monitoring, indicating that even in the presence of genetic and physiological vulnerability, parents can influence the likelihood of offspring developing problematic alcohol-related behaviors.

Population differences in associations of serotonin transporter promoter polymorphism (5HTTLPR) di- and triallelic genotypes with blood pressure and hypertension prevalence

Based on prior research finding the 5HTTLPR L allele associated with increased cardiovascular reactivity to laboratory stressors and increased risk of myocardial infarction, we hypothesized that the 5HTTLPR L allele will be associated with increased blood pressure (BP) and increased hypertension prevalence in 2 large nationally representative samples in the United States and Singapore.

METHODS

Logistic regression and linear models tested associations between triallelic (L'S', based on rs25531) 5HTTLPR genotypes and hypertension severity and mean systolic and diastolic blood pressure (SBP and DBP) collected during the Wave IV survey of the National Longitudinal Study of Adolescent to Adult Health (Add Health, N=11,815) in 2008-09 and during 2004-07 in 4196 Singaporeans.

RESULTS

In US Whites, L' allele carriers had higher SBP (0.9 mm Hg, 95% CI=0.26-1.56) and greater odds (OR=1.23, 95% CI=1.10-1.38) of more severe hypertension than those with S'S' genotypes. In African Americans, L' carriers had lower mean SBP (-1.27mm Hg, 95% CI=-2.53 to -0.01) and lower odds (OR = 0.78, 95% CI=0.65-0.94) of more severe hypertension than those with the S'S' genotype. In African Americans, those with L'L' genotypes had lower DBP (-1.13mm Hg, 95% CI=-2.09 to -0.16) than S' carriers. In Native Americans, L' carriers had lower SBP (-6.05mm Hg, 95% CI=-9.59 to -2.51) and lower odds of hypertension (OR = 0.34, 95% CI=0.13-0.89) than those with the S'S' genotype. In Asian/Pacific Islanders those carrying the L' allele had lower DBP (-1.77mm Hg, 95% CI=-3.16 to -0.38) and lower odds of hypertension (OR = 0.68, 95% CI=0.48-0.96) than those with S'S'. In the Singapore sample S' carriers had higher SBP (3.02mm Hg, 95% CI=0.54-5.51) and DBP (1.90mm Hg, 95% CI=0.49-3.31) than those with the L'L' genotype.

CONCLUSIONS

These findings suggest that Whites carrying the L' allele, African Americans and Native Americans with the S'S' genotype, and Asians carrying the S' allele will be found to be at higher risk of developing cardiovascular disease and may benefit from preventive measures.

Serotonin Transporter Genetic Variation is Differentially Associated with Reflexive- and Reflective-Optimal Learning

Learning to respond optimally under a broad array of environmental conditions is a critical brain function that requires engaging the cognitive systems that are optimal for solving the task at hand. Serotonin is implicated in learning and decision-making, but the specific functions of serotonin in system-level cognitive control remain unclear. Across 3 studies, we examined the influence of a polymorphism within the promoter region of the serotonin transporter gene (5-HTTLPR polymorphism in SLC6A4) on participants' ability to engage the task appropriate cognitive system when the reflexive (Experiments 1 and 2) or the reflective (Experiment 3) system was optimal. Critically, we utilized a learning task for which all aspects remain fixed with only the nature of the optimal cognitive processing system varying across experiments. Using large community samples, Experiments 1 and 2 (screened for psychiatric diagnosis) found that 5-HTTLPR S/LG allele homozygotes, with putatively lower serotonin transport functionality, outperformed LA allele homozygotes in a reflexive-optimal learning task. Experiment 3 used a large community sample, also screened for psychiatric diagnosis, and found that 5-HTTLPR LA homozygotes, with putatively higher serotonin transport functionality, outperformed S/LG allele homozygotes in a reflective-optimal learning task.

Variation in mothers' arginine vasopressin receptor 1a and dopamine receptor D4 genes predicts maternal sensitivity via social cognition

We examined the extent to which the arginine vasopressin receptor 1a (AVPR1a) and dopamine receptor D4 (DRD4) were related to sensitive maternal behavior directly or indirectly via maternal social cognition. Participants were 207 (105 European-American and 102 African-American) mothers and their children (52% females). Sensitive maternal behavior was rated and aggregated across a series of tasks when infants were 6 months, 1 year and 2 years old. At 6 months, mothers were interviewed about their empathy, attributions about infant behavior and beliefs about crying to assess their parenting-related social cognition. Mothers with long alleles for AVPR1a and DRD4 engaged in more mother-oriented social cognition (i.e. negative attributions and beliefs about their infants' crying, β = 0.13, P < 0.05 and β = 0.16, P < 0.05, respectively), which in turn predicted less sensitive maternal behavior (β = -0.23, P < 0.01). Both indirect effects were statistically significant independent of one another and covariates [95% confidence interval (CI): -0.22, -0.03 and β = -0.03 for AVPR; 95% CI: -0.20, -0.03 and β = -0.04 for DRD4]. There were no significant direct effects of AVPR1a or DRD4 on maternal sensitivity (β = 0.02, P = .73 and β = -0.10, P = .57, respectively). The results did not vary for African-American and European-American mothers (Δχ²  = 18.76, Δdf = 16, P = 0.28). Results support the view that one mechanism by which maternal genes are associated with parental behavior is via social cognition.

Depression, Stressful Life Events, and the Impact of Variation in the Serotonin Transporter: Findings from the National Longitudinal Study of Adolescent to Adult Health (Add Health)

Background

The low transcriptionally efficient short-allele of the 5HTTLPR serotonin transporter polymorphism has been implicated to moderate the relationship between the experience of stressful life events (SLEs) and depression. Despite numerous attempts at replicating this observation, results remain inconclusive.

Methods

We examined this relationship in young-adult Non-Hispanic white males and females between the ages of 22 and 26 (n = 4724) participating in the National Longitudinal Study of Adolescent to Adult Health (Add Health) with follow-up information every six years since 1995.

Results

Linear and logistic regression models, corrected for multiple testing, indicated that carriers of one or more of the S-alleles were more sensitive to stress than those with two L-alleles and at a higher risk for depression. This relationship behaved in a dose-response manner such that the risk for depression was greatest among those who reported experiencing higher numbers of SLEs. In post-hoc analyses we were not able to replicate an interaction effect for suicide ideation but did find suggestive evidence that the effects of SLEs and 5HTTLPR on suicide ideation differed for males and females. There were no effects of childhood maltreatment.

Discussion

Our results provide partial support for the original hypothesis that 5-HTTLPR genotype interacts with the experience of stressful life events in the etiology of depression during young adulthood. However, even with this large sample, and a carefully constructed a priori analysis plan, the results were still not definitive. For the purposes of replication, characterizing the 5HTTLPR in other large data sets with extensive environmental and depression measures is needed.

Association of polymorphisms in 5-HTT (SLC6A4) and MAOA genes with measures of obesity in young adults of Portuguese origin

OBJECTIVES

To investigate the association of polymorphisms in SLC6A4 and MAOA genes with overweight (including obesity).

MATERIAL AND METHODS

Young adults (n = 535) of Portuguese origin were genotyped for the SLC6A4 polymorphisms 5-HTTLPR and STin2 and a MAOA VNTR. BMI and body fat percentage were measured and a questionnaire was used to assess individual's sport practicing habits.

RESULTS

In whole study sample, haplotype-based analysis revealed significant association with overweight/obesity for the individual 5-HTTLPR/Stin2 haplotype L10 (p = 0.04). In men, the MAOA 3R genotype was nominally associated with body fat (p = 0.04). In inactive individuals, overweight/obesity was found significantly associated with 5-HTTLPR L-allele (p = 0.01) and nominally associated with STin2 10-allele (p = 0.03). A significant association was also found testing for all haplotype effects (χ(2 )= 8.7; p = 0.03).

CONCLUSIONS

We found some evidences for the association of SLC6A4 and MAOA genes with measures of obesity. Our results suggest physical inactivity accentuates the influence of SLC6A4 polymorphisms on obesity risk.