DRD2 Taq1A Polymorphism Research Articles

Association between dopamine receptor D2 Taq IA gene polymorphism (rs1800497) and personality traits.

This study aimed to find a potential association between the DRD2 Taq1A gene polymorphism (rs1800497 C32806T) and personality traits. In all, 249 youths were recruited for this study. The Short-form Revised Eysenck Personality Questionnaire was administered to assess personality traits. The participants were genotyped for the DRD2 Taq1A polymorphism using the polymerase chain reaction-restriction fragment length polymorphism method. Statistical analysis was carried out to find a possible association between the genotypes and aspects of personality traits assessed. The frequencies of the A1 and A2 alleles in our sampled population were 215 (43.2%) and 283 (56.8%), while the frequencies of A1A1, A1A2, and A2A2 were 67 (26.9%), 81 (32.5%), and 101 (40.6%), respectively. The study population was not in Hardy-Weinberg equilibrium (χ2 = 17.64, p < 0.001). The A2 allele was significantly associated with extraversion. Although this allele was also associated with neuroticism, psychoticism, and lie, the association was not significant. The A2 allele of the DRD2 Taq1A polymorphism was found to be more associated with extraversion, as measured by the Short-form Revised Eysenck Personality Questionnaire.

Evaluation of the Relationship Between Dopamine Receptor D2 Gene TaqIA1 Polymorphism and Alcohol Dependence Risk.

Several studies are published, that investigated dopamine receptor 2 (DRD2) gene TaqIA polymorphism as a risk factor for alcohol dependence (AD) with positive and negative associations. To derive a more precise estimation of the relationship, a meta-analysis of case-control studies that examined the association between DRD2 gene Taq1A polymorphism and alcohol dependence was performed. Eligible articles were identified through a search of databases including PubMed, Science Direct, Springer link, and Google Scholar. The association between the DRD2 TaqIA polymorphism and AD susceptibility was conducted using odds ratios (ORs) and 95% confidence intervals (95% CIs) as association measures. A total of 69 studies with 9125 cases and 9123 healthy controls were included in the current meta-analysis. Results of the present analysis showed significant association between DRD2 TaqIA polymorphism and AD risk using five genetic modes (allele contrast model-OR 1.22, 95% CI 1.13-1.32, p < 0.0001; homozygote model-OR 1.35, 95%CI 1.18-1.55; p ≤ 0.0001; dominant model-OR 1.29; 95% CI 1.20-1.39; p < 0.0001; recessive model-OR 1.21; 95% CI 1.08-1.36; p = 0.0006). There was no significant association found in subgroup analysis, TaqIA polymorphism was not significantly associated with AD risk in the Asian population under all genetic models, but in the Caucasian population, TaqIA polymorphism was significantly associated with AD risk. Overall, results support the hypothesis that DRD2 Taq1A polymorphism plays a role in alcohol dependence.

Associations among SNPs in two addictive genes, food addiction, and antioxidant markers in recreationally active young women.

Introduction: food addiction is associated with genetic polymorphisms and decreased antioxidant intake. Objectives: this study determined the associations among food addiction, dopamine receptor 2 (DRD2) and toll-interleukin 1 receptor (TIR) domain-containing adaptor protein (TIRAP rs625413) gene polymorphisms, antioxidant capacities, and zinc levels among recreationally active Turkish women. Methods: the Yale Food Addiction Scale was used to evaluate the food addiction status. Serum antioxidant capacities and zinc levels were evaluated by blood analyses. Deoxyribonucleic acid (DNA) extraction was performed using peripheral blood leukocytes, and the polymorphism status of the DRD2 Taq 1A and TIRAP genes was investigated using a commercial kit. Results: the frequencies of the heterozygous genotypes of DRD2 Taq 1A and TIRAP were 23.1 % and 31.4 %, respectively, and the frequency of risk allele homozygous genotypes was 3.2 %. Most participants (94.4 %) had a nonpolymorphic/wild (CC) genotype in both genes; however, 11.5 % of the participants had a food addiction. The differences between serum antioxidant capacities, zinc levels, and body mass indices of those with and without food addiction were statistically significant. However, there were no differences in the serum zinc and antioxidant levels among the different genotypes. Conclusion: food addiction in young Turkish women was not associated with DRD2 Taq 1A or TIRAP polymorphisms but was associated with serum antioxidant capacities and zinc levels. Further studies on different loci of the same genes or genotypes of different genes with larger sample sizes are warranted.

Clustering of Parkinson subtypes reveals strong influence of DRD2 polymorphism and gender

Most classification approaches for idiopathic Parkinson’s disease subtypes primarily focus on motor and non-motor symptoms. Besides these characteristics, other features, including gender or genetic polymorphism of dopamine receptors are potential factors influencing the disease’s phenotype. By utilizing a kmeans-clustering algorithm we were able to identify three subgroups mainly characterized by gender, DRD2 Taq1A (rs1800497) polymorphism—associated with changes in dopamine signaling in the brain—and disease progression. A subsequent regression analysis of these subgroups further suggests an influence of their characteristics on the daily levodopa dosage, an indicator for medication response. These findings could promote further enhancements in individualized therapies for idiopathic Parkinson’s disease.

The DRD2 Taq1A polymorphism moderates the effect of PTSD symptom severity on the left hippocampal CA3 volume: a pilot study

Rationale and objectivesThe hippocampus, especially the CA1, CA3, and dentate gyrus (DG) subfields, is reported to be associated with post-traumatic stress disorder (PTSD) after trauma. However, neuroimaging studies of the associations between PTSD and hippocampal subfield volumes have failed to yield consistent findings. The aim of this study is to examine whether the dopamine D2 receptor (DRD2) Taq1A polymorphism, which is associated with both hippocampal function and PTSD, moderated the association between PTSD severity and hippocampal CA1, CA3 and DG volumes.MethodsT1-weighted images were acquired from 142 trauma survivors from the 2008 Wenchuan earthquake using a 3.0-T magnetic resonance imaging system. Hippocampal subfield segmentations were performed with FreeSurfer v6.0. We used the simple moderation model from the PROCESS v3.4 tool for SPSS 23.0 to examine the association between the rs1800497 polymorphism, PTSD severity, and hippocampal CA3 and DG volumes.ResultsA significant genotype × PTSD symptom severity interaction was found for the left CA3 volume (ΔF = 5.01, p = 0.008, ΔR2 = 0.05). Post hoc, exploratory analyses deconstructing the interaction revealed that severe PTSD symptomatology were associated with reduced left CA3 volume among TC heterozygotes (t = − 2.86, p = 0.005).ConclusionsThis study suggests that DRD2 Taq1A polymorphism moderates the association between PTSD symptomatology and left CA3 volume, which promotes an etiological understanding of the hippocampal atrophy at the subfield level. This highlights the complex effect of environmental stress, and provides possible mechanism for the relationship between the dopaminergic system and hippocampal function in PTSD.

Pharmacogenomic Studies in Intellectual Disabilities and Autism Spectrum Disorder: A Systematic Review.

Individuals with intellectual disability (ID) and autism spectrum disorder (ASD) often receive psychotropic medications such as antipsychotics and antidepressants to treat aberrant behaviors and mood symptoms, frequently resulting in polypharmacy and drug-related adverse effects. Pharmacogenomic (PGx) studies with ASD and/or ID (ASD/ID) have been scarce despite the promise of optimizing treatment outcomes. We reviewed the literature on PGx studies with antipsychotics and antidepressants (e.g., treatment response and adverse effects) in ASD/ID. We performed a systematic review using MEDLINE, Embase, and PsycINFO, including peer-reviewed original articles in English referring to PGx in the treatment of ASD/ID in any age groups (e.g., treatment response and adverse effects). A total of 28 PGx studies using mostly candidate gene approaches were identified across age groups. Notably, only 3 studies included adults with ASD/ID while the other 25 studies focused specifically on children/adolescents with ASD/ID. Twelve studies primarily investigated treatment response, of which 5 and 6 studies included patients treated with antipsychotics and antidepressants, respectively. Most interesting results for response were reported for 2 sets of candidate gene studies, namely: (1) The DRD3 Ser9Gly (rs6280) polymorphism was examined in patients treated with risperidone in 3 studies, 2 of which reported an association with risperidone treatment response and (2) the SLC6A4 5-HTTLPR polymorphism and treatment response to antidepressants which was investigated in 4 studies, 3 of which reported significant associations. In regard to side effects, 9 of 15 studies focused on hyperprolactinemia in patients treated with risperidone. Among them, 7 and 5 studies examined the impact of CYP2D6 and DRD2 Taq1A polymorphisms, respectively, yielding mostly negative study findings. There is limited data available on PGx in individuals with ASD/ID and in particular in adults. Given the potential for PGx testing in improving treatment outcomes, additional PGx studies for psychotropic treatment in ASD/ID across age groups are warranted.

The association between perinatal hypoxia exposure and externalizing symptoms and children's decision making in conditions of uncertainty is moderated by DRD2 genotype.

Variants of the DRD2 Taq1A polymorphism, which have been shown to result in functional differences in dopamine D2 receptors (D2R), have been linked to various externalizing outcomes in adults. However, the neurobiological processes that contribute to these associations are not well understood. The current study investigates gene×environment effects on teacher-rated externalizing behaviors and probabilistic decision making in a sample of 333 children (age 9) enrolled in an ongoing longitudinal study. Findings indicate that externalizing behaviors increased as a function of hypoxic exposure only among individuals carrying the A1 (A1+) allele. Results also indicate that willingness to pursue reward under conditions of maximum uncertainty (50% probability) decreased as a function of hypoxic exposure only among A1- individuals. Among A1 carriers, no association between probability decision making and hypoxic exposure emerged. These findings suggest that hypoxia could influence neural development through different biological pathways depending on D2 receptor genotype, and provide insight into the development of individual differences in behavior and decision making.

The combined effect of CYP2D6 and DRD2 Taq1A polymorphisms on the antipsychotics daily doses and hospital stay duration in schizophrenia inpatients (observational naturalistic study).

To assess the correlation between the antipsychotics (AP) mean daily doses, hospital stay duration and CYP2D6, DRD2 polymorphisms in naturalistic study. CYP2D6 polymorphisms *3, *4, *5, *6, *1XN and DRD2/ANKK1 Taq1A polymorphisms were genotyped in a cohort of 226 Caucasian schizophrenic inpatients. AP daily doses, hospital stay duration and AP treatment duration were taken from medical records. To compare mean daily doses of AP among CYP2D6 PMs, EMs, UMs and DRD2/ANKK1 Taq1A carriers the actual AP doses were converted to chlorpromazine (CPZ) equivalents and DDD (defined daily dose). Significant correlation (p=0.004) between CYP2D6 metabolic activity and AP mean daily doses was observed only among DRD2/ANKK1 Taq1A polymorphic allele carriers: 250.53 (95%CI: 154.90-346.17), 473.82 (95%CI: 426.99-520.64) 602.77 (95%CI: 469.65-735.88) CPZ equivalents in PMs, EMs and UMs, consequently. PMs with DRD2/ANKK1 Taq1A CT genotype received significantly lower doses of AP comparing to CC genotype (p=0.02). Mean hospital stay duration of PMs+UMs was significantly higher comparing to EMs (66.4 days (95% CI: 56.9-75.8) vs 50.2 days (95%CI: 45.5-54.7); p=0.047). In a cohort of schizophrenia inpatients CYP2D6 metabolic activity affects mean AP daily dose only in the presence of DRD2 Taq1A polymorphic allele. CYP2D6 metabolic activity correlates independently from DRD2 Taq1A polymorphism with hospital stay duration. Subpopulation of schizophrenia inpatients with altered CYP2D6 activity (PMs and UMs) carriers of Taq1A polymorphisms needs special attention of clinicians in aligning of AP treatment.

Association of dopamine receptor D2 gene (DRD2) Taq1 polymorphisms with eating behaviors and obesity among Chinese and Indian Malaysian university students.

This study investigated the association of DRD2 Taq1A, Taq1B and Taq1D gene polymorphisms with eating behavior, the preference/intake frequency/craving of high-fat foods and obesity in 394 Malaysian adults (161 males, 233 females; 308 Chinese, 86 Indians; 67 obese, 327 non-obese). Eating behaviors namely Cognitive Restraint, Uncontrolled Eating and Emotional Eating scores were assessed by the Three Factor Eating Questionnaire-R18. The preference/intake frequency/craving of 26 common high-fat Malaysian foods was assessed using a 7-point hedonic scale. Anthropometric measurements were taken and Taq1 gene polymorphisms were genotyped by PCR-Restriction Fragment Length Polymorphism using DNA extracted from mouthwash samples. The overall minor allele frequencies of Taq1A, Taq1B and Taq1D according to ethnicities (Chinese/Indian) were 0.37/0.29, 0.39/0.28, 0.06/0.30, respectively; genotype and allele distributions of Taq1B and Taq1D were significantly different between ethnicities. Eating behaviorscores were not significantly different between gender and ethnicities. Those with A1 or B1 allele had lower Cognitive Restraint score and higher Uncontrolled Eating score, while those with A1/A1 or B1/B1 genotype had higher fast food preference. D1 allele was associated with increased starchy food craving and mamak (Malaysian Indian-Muslim) food preference, but not eating behavior scores. All three gene variants were not associated with obesity and adiposity. Taken together, we posit that three DRD2 Taq1 gene polymorphisms influence the eating behavior and preference/intake frequency/craving of certain high-fat foods in Malaysian adults, but their role in obesity and adiposity is still inconclusive and needs further investigation.

Impact of Pharmacogenetic Markers of CYP2D6 and DRD2 on Prolactin Response in Risperidone-Treated Thai Children and Adolescents With Autism Spectrum Disorders.

The aim of the study was to identify the impact of pharmacogenetic markers associated with prolactin concentration in risperidone-treated children and adolescents with autism spectrum disorders. One hundred forty-seven children and adolescents with autism, aged 3 to 19 years, received risperidone. The clinical data of patients were recorded from medical records. Prolactin levels were measured by chemiluminescence immunoassay. Three CYP2D6 single nucleotide polymorphisms, CYP2D6*4 (1846G>A), *10 (100C>T), and *41 (2988G>A), 1 gene deletion (*5), and DRD2 Taq1A (rs1800497) polymorphism were genotyped by TaqMan real-time polymerase chain reaction. The 3 common allelic frequencies were CYP2D6*10 (55.10%), *1 (32.65%), and *5 (6.12%), respectively. Patients were grouped according to their CYP2D6 genotypes. There was no significant correlation between the concentrations of prolactin among the CYP2D6 genotypes. In addition, there were no statistical differences in the prolactin response among the CYP2D6-predicted phenotypes of extensive metabolizer and intermediate metabolizer. The DRD2 genotype frequencies were Taq1A A2A2 (38.77%), A1A2 (41.50%), and A1A1 (19.73%), respectively. There were statistically significant differences in prolactin level of patients among the 3 groups (P = 0.033). The median prolactin level in patients with DRD2 Taq1A A2A2 (17.80 ng/mL) was significantly higher than A1A2 (17.10 ng/mL) and A1A1 (12.70 ng/mL). DRD2 Taq1A A2A2 polymorphisms may play a significant role in the hyperprolactinemia- associated with risperidone treatment in children and adolescent with autism spectrum disorder. Many drugs used chronically in psychiatric diseases exert their effects mainly through the dopamine D2 receptor. It is therefore possible that these drugs could alter the expression of any dopamine receptor, thus affecting the pharmacodynamics characteristics and toxicity of drug substrates during pharmacotherapy.

Impact of DRD2 polymorphisms on prolactin level in risperidone-treated Thai children and adolescent with autism spectrum disorders

IntroductionA large number of studies have reported that the prolactin concentration was significantly increased in the Taq1A A1 allele carriers because several reports revealed that individuals with the DRD2 Taq1A A1 allele have a reduced density of brain D2 receptors.ObjectiveThe main aim of this study was to identify the impact of pharmacogenetic markers associated with prolactin concentration in risperidone-treated children and adolescents with autism spectrum disorders.MethodsOne hundred and forty-seven children and adolescents with autism, aged 3 to 19, received risperidone. The clinical data of patients were recorded from medical records. Prolactin levels were measured by chemiluminescence immunoassay. Three CYP2D6 single nucleotide polymorphisms (SNPs), CYP2D6*4 (1846G&gt;A), *10 (100C&gt;T), and *41 (2988G&gt;A), one gene deletion (*5), and DRD2 Taq1A (rs1800497) polymorphism were genotyped by TaqMan real-time PCR.ResultsThe three common allelic frequencies were CYP2D6*10 (55.10%), *1 (32.65%) and *5 (6.12%), respectively. Patients were grouped according to their CYP2D6 genotypes. The DRD2 genotype frequencies were Taq1A A2A2 (38.77%), A1A2 (41.50%), and A1A1 (19.73%), respectively. There were statistically significant differences in prolactin level of patients among the three groups (P = 0.033). The median prolactin level in patients with DRD2 Taq1A A2A2 (17.80 ng/mL) was significantly higher than A1A2 (17.10 ng/mL) and A1A1 (12.70 ng/mL).ConclusionDRD2 Taq1A A2A2 polymorphisms may be a critical role in an influence prolactin elevation during risperidone treatment in ASD.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Genetic-linked Inattentiveness Protects Individuals from Internet Overuse: A Genetic Study of Internet Overuse Evaluating Hypotheses Based on Addiction, Inattention, Novelty-seeking and Harm-avoidance

The all-pervasive Internet has created serious problems, such as Internet overuse, which has triggered considerable debate over its relationship with addiction. To further explore its genetic susceptibilities and alternative explanations for Internet overuse, we proposed and evaluated four hypotheses, each based on existing knowledge of the biological bases of addiction, inattention, novelty-seeking, and harm-avoidance. Four genetic loci including DRD4 VNTR, DRD2 Taq1A, COMT Val158Met and 5-HTTLPR length polymorphisms were screened from seventy-three individuals. Our results showed that the DRD4 4R/4R individuals scored significantly higher than the 2R or 7R carriers in Internet Addiction Test (IAT). The 5-HTTLPR short/short males scored significantly higher in IAT than the long variant carriers. Bayesian analysis showed the most compatible hypothesis with the observed genetic results was based on attention (69.8%), whereas hypotheses based harm-avoidance (21.6%), novelty-seeking (7.8%) and addiction (0.9%) received little support. Our study suggests that carriers of alleles (DRD4 2R and 7R, 5-HTTLPR long) associated with inattentiveness are more likely to experience disrupted patterns and reduced durations of Internet use, protecting them from Internet overuse. Furthermore, our study suggests that Internet overuse should be categorized differently from addiction due to the lack of shared genetic contributions.

Lack of association between DRD2 Taq1A gene polymorphism and smoking cessation therapy: a meta-analysis

Recent studies have reported that genetic factors are significantly associated with smoking behavior, but the influence of the smoking behavior-related genes on smoking cessation treatment is still not clear. We analyzed the smoking cessation outcomes among previously reported studies involving participants who underwent smoking cessation therapy by comparing the following DRD2 Taq1A gene polymorphism using meta-analysis. In total, nine studies including 2,851 participants were assessed and the A1 allele carriers and A2 homozygotes were compared with respect to smoking cessation outcomes by meta-analysis. No significant association was observed for the main analysis (OR = 0.900; 95% CI, 0.751 - 1.078). In subgroup analysis, three studies were assessed by comparing participants with the A1/A1, A1/A2, and A2/A2 genotypes. A significant association between the DRD2 Taq1A polymorphism and< smoking cessation therapy was observed between the A1/A1 and A1/A2 genotypes (OR = 2.967; 95% CI 1.737 - 5.068) and between the A1/A2 and A2/A2 genotypes (OR = 0.547; 95% CI 0.392 - 0.762), but not between the A1/A1 and A2/A2 genotypes (OR = 1.269; 95% CI 0.746 - 2.157). This study is the first meta-analysis to evaluate and quantitatively integrate the association between the DRD2 Taq1A polymorphism and smoking cessation therapy. A significant relationship between DRD2 Taq1A polymorphism and smoking cessation therapy was not observed.

Polymorphisms influencing olanzapine metabolism and adverse effects in healthy subjects

The pharmacokinetics of olanzapine and response to treatment could be affected by polymorphisms in genes coding for drug-metabolizing enzymes, transporters, or receptors. The aim of this study was to identify genetic markers predictive of pharmacokinetics, pharmacodynamics, and adverse effects of olanzapine. Sixty-three healthy volunteers receiving a single 5-mg oral dose of olanzapine were genotyped for 39 genetic variants that could be related to the response to olanzapine. All genetic variants were analyzed by PharmaChip, but DRD2 Taq1A polymorphism was determined by real-time polymerase chain reaction. Olanzapine was measured using high-performance liquid chromatography combined with tandem mass spectrometry. The relationship of gender and polymorphisms with olanzapine pharmacokinetics, the change in prolactin levels, and the incidence of adverse effects were evaluated by multiple regression analysis. The pharmacokinetics of olanzapine was influenced by polymorphisms in CYP3A5, GSTM3, and GRIN2B. Prolactin levels were affected by gender and polymorphisms in DRD2 and 5-HTR2A. Polymorphisms in CYP2C9, TPMT, UGT1A1, MDR1, and 5-HTR2A were related to some adverse effects of olanzapine. Several polymorphisms can explain differences in the pharmacokinetics, pharmacodynamics, and safety of olanzapine in healthy subjects. Whether these genetic factors influence the risk of therapeutic failure or tolerability in patients remains to be established.

BDNF Val66Met and DRD2 Taq1A polymorphisms interact to influence PTSD symptom severity: A preliminary investigation in a South African population

We evaluated the role that selected variants in serotonin transporter (5-HTT), dopamine receptor 2 (DRD2) and brain-derived neurotrophic factor (BDNF) genes play in PTSD symptom severity in an at-risk population. We also investigated the interaction between the genetic variants to determine whether these variables and the interactions between the variables influenced the severity of PTSD symptoms. PTSD symptoms were quantitatively assessed using the Davidson Trauma Scale (DTS) in 150 participants from an at-risk South African population. All participants were genotyped for the 5-HTTLPR, DRD2 Taq1A and BDNF Val66Met polymorphisms. Gene-gene interactions were investigated using various linear models. All analyses were adjusted for age, gender, major depressive disorder diagnosis, level of resilience, level of social support and alcohol dependence. A significant interaction effect between DRD2 Taq1A and BDNF Val66Met variants on DTS score was observed. On the background of the BDNF Val66Val genotype, DTS score increased significantly with the addition of a DRD2 Taq1A A1 allele. However, on the BDNF Met66 allele background, the addition of an A1 allele was found to reduce total DTS score. This study provides preliminary evidence for an epistatic interaction between BDNF Val66Met and DRD2 Taq1A polymorphisms on the severity of PTSD symptoms, where both too little and too much dopamine can result in increased PTSD symptom severity.

Childhood Obesity and the Role of Dopamine D2 Receptor and Cannabinoid Receptor-1 Gene Polymorphisms

The dopaminergic and endocannabinoid systems are involved in regulation of feeding behavior. The aim of the study is to examine the possible relation between polymorphisms of the dopamine D2 receptor (DRD2) and cannabinoid receptor-1 (CNR1) genes and childhood obesity. A hundred obese children and 100 healthy controls were analyzed for DRD2 Taq1A and Taq1B and CNR1 1359G/A polymorphisms. Genotyping was performed by polymerase chain reaction and restriction fragment length polymorphism. There were no statistically significant differences in DRD2 Taq1A and DRD2 Taq1B genotypes or allelic frequencies between obese children and controls (p>0.05). In patients with Taq1B2 allele, morbid obesity was less frequent (p=0.010). The frequency of the A allele of CNR1 1359G/A polymorphism was significantly higher in obese children than in controls (21.0% vs. 13.0%, p=0.0166). The frequency of genotypes AG and GG of the CNR1 1359G/A SNP was different between obese children and control subjects (for AG: 34.0% vs. 22.0%, p=0.0294; for GG: 62.0% vs. 76.0%, p=0.0162, respectively). No significant difference was found between genotypes and alleles of DRD2 Taq1A and DRD2 Taq1B polymorphism in patients and controls, while the CNR1 receptor 1359G/A polymorphism and the presence of the A allele may be one risk factor for susceptibility to obesity.

Dopamine-system genes, childhood abuse, and clinical manifestations in women with Bulimia-spectrum Disorders

ObjectiveWe explored interaction effects involving polymorphisms of targeted dopamine system genes and selected forms of childhood abuse (sexual, physical and emotional) acting upon severity of binge-eating and psychopathological symptoms in women with Bulimia-Spectrum Disorders (BSDs). MethodsWomen diagnosed with a BSD (n = 216) were assessed for childhood traumata, eating-disorder (ED) symptoms, and selected psychopathological features (sensation seeking, impulsivity, compulsivity and affective instability), and then provided blood samples for genotyping of main polymorphisms of dopamine-2 receptor (DRD2), dopamine transporter (DAT1) and catechol o-methyltransferase (COMT) genes. ResultsSensation Seeking was elevated in carriers of the low-function allele of the DRD2 Taq1A polymorphism who also reported childhood sexual abuse, relative to that in individuals showing other combinations of alleles and abuse exposures. In addition, carriers of a low-function allele of COMT scored higher on compulsivity, lower on impulsivity, and marginally lower on frequency of binge-eating than did individuals in whom the allele was absent. DiscussionOur results suggest that genes acting within the dopamine system may contribute, either directly or indirectly (i.e., in interaction with traumatic childhood experiences), to variations in the presentation of comorbid traits and, possibly, of bulimic symptoms.

DRD2 Taq1A Polymorphism Modulates Prolactin Secretion Induced by Atypical Antipsychotics in Healthy Volunteers

Hyperprolactinemia mediated by antagonism of dopaminergic neurotransmission in the pituitary gland is a common adverse effect of antipsychotics. Recent studies have suggested that polymorphisms of dopamine receptors can affect the therapeutic response to antipsychotics. Thus, our aim was to evaluate whether 2 such polymorphisms (DRD2 Taq1A and DRD3 Ser9Gly) modulate prolactin release in healthy volunteers (n = 119) receiving a single dose of quetiapine (25 mg, n = 26), olanzapine (5 mg, n = 57), or risperidone (1 mg, n = 36). The increases in maximum concentration and in area under the curve were calculated from plasma prolactin levels after subtraction of pretreatment levels. Multiple regression analyses revealed that prolactin increases in maximum concentration and in area under the curve depended on drug (quetiapine < olanzapine < risperidone; P < 0.001), sex (women > men; P < 0.001), and Taq1A polymorphism (A1⁺ > A2/A2; P < 0.05). Analysis of the individual drugs revealed that prolactin secretion was modulated by sex and Taq1A polymorphism in olanzapine and risperidone (P < 0.05); however, these factors were not linked to prolactin secretion in quetiapine.

Allele and Genotype Frequencies of Serotonin and Dopamine Transporter and Receptor Polymorphisms in a Norwegian Population

Polymorphisms in genes coding for dopaminergic and serotonergic receptors and transporters have been associated with the clinical effects and adverse drug reactions of antipsychotic and antidepressant drugs. The objective of this study was to investigate the frequency and combinations of common polymorphisms in the dopamine transporter (DAT1), dopamine D(2) receptor (DRD2), dopamine D(3) receptor (DRD3), serotonin transporter (5HTT), and serotonin 2A receptor (5HTR2A) genes in a Norwegian population. To determine the background frequency in the population, 250 blood samples were consecutively collected from healthy Norwegian blood donors (125 men and 125 women; mean age: 48±11 years). Samples were tested for DAT1 VNTR, DRD2 Taq1A, DRD3 Ser9Gly, 5HTTLPR, and four polymorphisms (102 T>C, His452Tyr, 516 C>T, and Thr25Asn) in the 5HTR2A, using polymerase chain reaction and real-time polymerase chain reaction. We observed the frequency of the nine-repeat allele of DAT1 VNTR polymorphism as 20% (95% confidence interval [CI]: 0.18-0.23), the A1 allele of DRD2 Taq1A polymorphism as 21% (95% CI: 0.19-0.23), the A1 allele of DRD3 Ser9Gly polymorphism as 68% (95% CI: 0.66-0.70), the short allele of 5HTTLPR as 38% (95% CI: 0.36-0.40), and the T allele of 5HTR2A 102 T>C polymorphism as 41% (95% CI: 0.39-0.41), and the frequencies of 5HTR2A His452Tyr and 5HTR2A Thr25Asn were 93% and 95%, respectively. The tested polymorphisms showed differences compared with other European populations. Further studies are necessary to better understand the effect of these alleles and their combinations on personality, mental disorders, drug response, and adverse reactions of psychotropic drugs.

P.6.007 Effect of L-glutamine and its dipeptides on the level of voluntary alcohol consumption in rats

We have performed a case-control analysis of dopamine D2-like receptor (DRD2, DRD3 and DRD4) gene polymorphisms in 118 Han Chinese cases with bipolar affective disorder and 196 control subjects, and replication analysis in 157 English cases and 143 control subjects. We found association between a functional DRD2 promoter variant (P=0.03 by allele) and the DRD2 taq1A polymorphism (P=0.001 by allele) in Chinese bipolar disorder patients. However, this finding was not replicated in the Caucasian subjects, indicating that the significant association we observed in the Chinese population is a false positive finding. An alternative explanation is that these polymorphisms are risk factors in Chinese but not Caucasian populations, a hypothesis which seems unlikely in view of the similarity of the clinical characteristics of bipolar disorder in the two populations. We also report a novel, rare one-repeat variant of the DRD4 exon 3 VNTR repeat in Chinese populations, which appears to be absent in Caucasians and is not associated with disease.