DRD2 Research Articles

Effects of Smoking on Aggression, Big Five Personality Factors, and Polymorphisms in HTR2A, DRD4, and MAOA among Egypt University Students.

Introduction To find genetic variants in the DRD4 and HTR2A genes' promoter regions and exons that are associated with tobacco smoking and nicotine addiction in Egyptian university students as well as to study the association between personality traits and smoking status. Methods A self-administered questionnaire about cigarette smoking and personality attributes (Big Five Inventory, ESPAD Questionnaire on Substance Abuse, and Buss-Perry Aggression Questionnaire). The participants in the study were 90 nonsmokers (NS) and 88 current smokers (CS), who were divided into two groups depending on their cigarette consumption per day (cpd): 55 heavy smokers (HS, >20 cpd) and 33 light smokers (LS, 1–10 cpd). Four and eight single nucleotide polymorphisms (SNPs) in the DRD4, HTR2A, and MOA genes, respectively, were genotyped. Results Smokers scored lower on neuroticism, agreeableness, conscientiousness, openness, and extraversion than nonsmokers, but higher on aggression. Furthermore, the C allele of rs1800955 in DRD4 was associated with cigarette smoking in the HS vs. NS and LS vs. NS studies. The T allele of the HTR2A rs6313 gene was discovered to be strongly associated with cigarette smoking. There was no link discovered between MOA rs1137070 and MOA rs1137070. Conclusions Using a comprehensive personality model (FFM), this study repeats and extends earlier research. Personality and genetic studies may aid in the development of a more complete and conclusive understanding of cigarette smoking, as well as more precise policies and guidelines for smoking cessation and quitting.

DRD2 and DRD3 genes, cannabis use and brain activity in first-episode psychosis

DRD2 and DRD3 genes, cannabis use and brain activity in first-episode psychosis

Association of Alcohol Use Disorder Risk With ADH1B, DRD2, FAAH, SLC39A8, GCKR, and PDYN Genetic Polymorphisms.

Alcohol use disorder (AUD) is a chronic, multifactorial psychiatric condition with an enormous impact on public health and social cost. Genetic studies suggest a heritability, and genome-wide association studies (GWAS) have revealed genetic polymorphisms influencing AUD development. Our study aimed to investigate known variants located in ADH1B, DRD2, FAAH, SLC39A8, GCKR, and PDYN genes (rs1229984, rs7121986, rs324420, rs13107325, rs1260326, rs2281285 respectively) in an AUD Greek cohort in order to shed more light on the genetic predisposition to AUD. Alcohol-dependent individuals (n=251) meeting both the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) and the ICD-10 guidelines for alcohol abuse and dependence, and control individuals (n=280) were recruited. DNA was extracted from whole blood and PCR-restriction fragment length polymorphism (RFLP-PCR) or allele-specific PCR method was used for genotyping. Individuals carrying the FAAH rs324420 A allele were significantly associated with increased risk of AUD (p<0.0001). SLC39A8 rs13107325 T allele and ADH1B rs1229984 T allele are overrepresented in control subjects (p<0.0001 and p<0.0001, respectively). The associations are maintained following an adjustment for age and sex and Bonferroni correction. GCKR rs13107325, DRD2 rs7121986, and PDYN rs2281285 polymorphisms did not show a significant association with AUD in the studied population after Bonferroni correction. Susceptibility to AUD is related to variations in FAAH, ADH1B, and SLC39A8 genes. These polymorphisms could serve as potential biomarkers for AUD risk.

Molecular Evaluation of Ex3 VNTR Polymorphism of the DRD4 Gene in Patients With Autism Spectrum Disorder.

Autism Spectrum Disorders (ASDs) are a group of neurodevelopmental disorders that affect social and communication skills. These diseases are characterized by severe communication and social skills disabilities and limited and repetitive activities. The prevalence of these disorders appears to be steadily increasing. It is proposed that the genes involved in the dopamine pathway may play an essential role in the development of autism. In this study, we investigated the possible association between Ex3 VNTR polymorphism of the DRD4 gene and autism spectrum disorders in the Iranian population. In this case-control study, 97 children with autism and 103 healthy individuals from a northwestern area of Iran as the case and control groups, respectively. After genomic xtraction from peripheral blood samples by the proteinase K method, the polymerase chain reaction (PCR) technique was used to determine the polymorphism genotypes. The data were then coded and analyzed using SPSS version 22 software. The study results showed that the allele frequencies differed in the two groups, some of them being statistically significant. The most common allele in both the ASD and the control group was the 700 bp allele, and its frequency was significantly different in the two groups and was more common in the ASD group (p-value=0.0018). The other allele with a statistically different frequency was the 800 bp allele which was less frequent in the ASD group (p-value=0.0017). These results suggest a potential association between Ex3 VNTR polymorphism of the DRD4 gene and autism spectrum disorder in the Iranian population. This necessitates further studies for the evaluation of the DRD4 gene.

Успешность распознавания лицевых экспрессий носителями различных генотипов генов COMT, DRD4, 5HT2A, MAOA

The work is aimed at describing the relationship between the genes COMT, DRD4, 5HT2A, MAOA with the success of facial expression recognition. These genes play an important role in various emotional and cognitive processes. At the same time, hereditary aspects of recognition of facial expressions, in contrast to sociocultural ones, have not been studied enough to date. The study involved 87 healthy students of Russian universities (20.4 ± 2.6 years). DNA analysis was carried out with the determination of genotypes by the polymorphic loci of the genes rs4680 COMT, rs6313 5HT2A (HTR2A), rs1800955 DRD4, VNTR MAOA (RSMU, Rostov-on-Don). The participants of the study were asked to distinguish emotional facial expressions in photographs taken from the MMI, KDEF, Rafd, WSEFEP image databases. The obtained results indicate the following differences in the success of facial expression recognition: carriers of the Val/Val genotype of the COMT gene significantly better recognize the emotions of surprise (H=7.7, df=2, p=0.02), fear (H=10.5, df=2, p=0.005), sadness (H=11.2, df=2, p=0.004); carriers of the heterozygous C/T genotype of the DRD4 gene significantly better recognize facial expression of disgust (H=9.1, df=2, p=0.01). No relationship was found between the MAOA gene genotypes and the success of emotion recognition.

Association of gene polymorphisms DRD3 rs6280, COMT rs4680 and HTR2A rs7322347 with schizophrenia

To check the association of genetic polymorphisms rs6280 of the DRD3 gene, rs4680 of the COMT gene, rs7322347 of the HTR2A gene with schizophrenia. The sample included 300 inpatients with paranoid schizophrenia. Inclusion criteria: age 18-50 years, established diagnosis «Schizophrenia, paranoid form», duration of psychiatric disorders not less than 5 years. The healthy control group consisted of 290 subjects. The association between polymorphisms and the study groups was assessed by logistic regression. The CC genotype of the rs6280 polymorphism is associated with schizophrenia (OR 3.37 (1.50; 8.03)). The TT genotype of the rs7322347 polymorphism is associated with controls (OR 1.83 (1.25; 2.68)). These analyses confirmed the hypothesis that the genetic polymorphisms rs7322347 of the HTR2A gene (p=0.006) and rs6280 of the DRD3 gene (p=0.004) were associated with the disease. The hypothesis of an association of the rs4680 polymorphism of the COMT gene could not be confirmed.

Emotional Intelligence in Carriers of Different СОМТ, BDNF, DRD2 and HTR2A Genotypes

Emotional intelligence is the ability to quickly and correctly recognize the emotional expressions of other people and to express and manage one's own emotions. It contributes to the success of a person in activities related to communication and interaction with people. Emotional intelligence has been studied largely in the context of organizational and education psychology, but less is known about the influence of genetics on it. We aim to study emotional intelligence in carriers of different СОМТ, BDNF, DRD2, and HTR2A genotypes. We used three methods to measure emotional intelligence. Mayer-Salovey-Caruso Emotional Intelligence Test is a set of tasks with forced choice and frequency-based correct responses. We also applied two self-report questionnaires by Lyusin and Hall. We recruited 280 participants who took part in all three measures. We also identified their genotypes of the СОМТ, BDNF, DRD2, and HTR2A genes. Carriers of the Val/Met genotype of the COMT gene, A/A genotype of the HTR2A gene and C/C genotype of the DRD2 gene showed the highest level of emotional intelligence, while no differences were found between carriers of the BDNF genotypes. These data were obtained by using the Mayer-Salovey-Caruso Emotional Intelligence Test. Self-report scores of emotional intelligence did not differ between carriers of different genotypes across all four of the genes in question. Mayer-Salovey-Caruso Emotional Intelligence Test scores were differed for carriers of some genotypes, whereas self-reported emotional intelligence scores did not differ between according to genotype.

Brain Magnetic Resonance Imaging Features of Nicotine-Dependent Individuals and Its Correlation with Polymorphisms of Dopamine D Receptor Gene.

The aim of this research was developed to provide a scientific basis for individualized prevention, clinical diagnosis, and corrective treatment of nicotine addiction. The objects were 214 cases in the smoke group and 43 cases in the control group. According to the Fagerstrom Nicotine Dependence Test (FTND), the smokers were divided into mild nicotine dependence group (FTND < 6 points, 138 cases) and nicotine severe dependence group (≥6 points, 76 cases). The brain structure in long-term smokers was evaluated by using magnetic resonance imaging (MRI). The nicotine dependence was further analyzed by grouping the included individuals, and some candidate genes related to nicotine addiction were screened by combining with bioinformatics analysis. The family research strategy was adopted to detect nicotine addiction susceptibility genes and their polymorphisms. The MRI imaging results showed that the bilateral thalamus, right parietal, and left lens gram-molecule volume (GMV) were negatively correlated with smoking index and smoking years in the smoking group. The GMV of the posterior cingulate cortex in the severe nicotine dependence group was lower than that of the control group, and the GMVs of bilateral thalamus and bilateral superior limbic gyrus in the mild nicotine dependence group were lower than those of the control group. The gene polymorphism detection showed that rs6275 was highly polymorphic in the target population and the frequency of rs6275-C allele was 53.26%. Therefore, the MRI imaging characteristics suggested that the affected brain regions of smokers and people with varying degrees of nicotine dependence were mainly concentrated in response-related pathways and the limbic system and had cumulative effects on the central nervous system. In addition, the M6275 polymorphism of DRD2 gene was associated with susceptibility to nicotine addiction in Chinese population, and the M6275-C allele had a protective effect on susceptibility to nicotine addiction and smoking initiation.

Characterization of Hemodynamic Alterations in Schizophrenia and Bipolar Disorder and Their Effect on Resting-State fMRI Functional Connectivity.

Common and distinct neural bases of Schizophrenia (SZ) and bipolar disorder (BP) have been explored using resting-state fMRI (rs-fMRI) functional connectivity (FC). However, fMRI is an indirect measure of neural activity, which is a convolution of the hemodynamic response function (HRF) and latent neural activity. The HRF, which models neurovascular coupling, varies across the brain within and across individuals, and is altered in many psychiatric disorders. Given this background, this study had three aims: quantifying HRF aberrations in SZ and BP, measuring the impact of such HRF aberrations on FC group differences, and exploring the genetic basis of HRF aberrations. We estimated voxel-level HRFs by deconvolving rs-fMRI data obtained from SZ (N = 38), BP (N = 19), and matched healthy controls (N = 35). We identified HRF group differences (P < .05, FDR corrected) in many regions previously implicated in SZ/BP, with mediodorsal, habenular, and central lateral nuclei of the thalamus exhibiting HRF differences in all pairwise group comparisons. Thalamus seed-based FC analysis revealed that ignoring HRF variability results in false-positive and false-negative FC group differences, especially in insula, superior frontal, and lingual gyri. HRF was associated with DRD2 gene expression (P < .05, 1.62 < |Z| < 2.0), as well as with medication dose (P < .05, 1.75 < |Z| < 3.25). In this first study to report HRF aberrations in SZ and BP, we report the possible modulatory effect of dopaminergic signalling on HRF, and the impact that HRF variability can have on FC studies in clinical samples. To mitigate the impact of HRF variability on FC group differences, we suggest deconvolution during data preprocessing.

Initial Study on COMT and DRD2 Gene Polymorphisms as Well as the Influence of Temperament and Character Trait on the Severity of Alcohol Craving in Alcohol-Dependent Patients.

The main aim of this work was to determine the impact of COMT and DRD2 gene polymorphisms together with temperament and character traits on alcohol craving severity alcohol-dependent persons. The sample comprised of 89 men and 16 women (aged ). For the sake of psychological assessment various analytic methods have been applied like the Short Alcohol Dependence Data Questionnaire (SADD), Penn Alcohol Craving Scale (PACS) or Temperament and Character Inventory (TCI) test. The SNP polymorphism of the analyzed genes was determined by Real Time PCR test. The results showed, that the COMT polymorphismmay have an indirected relationship with the intensity and changes in alcohol craving during abstinence. The DRD2 receptor gene polymorphisms are related with the intensity of alcohol craving. It seems that the character traits like “self-targeting”, including “self-acceptance”, are more closely related to the severity of alcohol craving and polymorphic changes in the DRD2 receptor than temperamental traits. Although this is a pilot study the obtained results appeared to be promising and clearly indicate the link betweengene polymorphisms alcohol craving and its severity.

Long-term effects of adolescent sport experience, DRD2 and COMT genes, and their interaction on sport participation in adulthood.

BackgroundThe present study investigated the joint impact of adolescent sport experience and dopamine‐related genes (i.e., DRD2 and COMT genes) on sport participation in adulthood.MethodsUsing the National Longitudinal Study of Adolescent Health (Add Health) data, the hierarchical multivariable logistic regression models for predicting sport participation in wave 3 (around 20 years of age) and wave 4 (around 30 years of age) were conducted separately by gender (male and female) and gene (DRD2 and COMT genes).ResultsAdolescent sport experience significantly interacted with the number of DRD2 A1 alleles and COMT Met alleles in affecting wave 3 sport participation among male adults. The interaction between adolescent sport experience and DRD2 gene significantly affected wave 4 sport participation in opposite direction to that affected wave 3 sport participation among male participants. Among female participants, there were no significant interaction effects between dopamine‐related genes and adolescent sport experience on sport participation in both wave 3 and 4.ConclusionsSince adult sport participation is most likely to be influenced by the joint impact of environmental and genetic factors, it is important to consider gene‐by‐environment interactions when designing policies or programs to promote adult sport participation.

Associations of CALM1 and DRD1 polymorphisms, and their expression levels, with Taihang chicken egg-production traits

Egg production by hens is an important reproductive performance index in the poultry industry. To investigate the effects of the CALM1 and DRD1 genes on egg production in chicken, their mRNA expression and single nucleotide polymorphisms (SNP) levels were investigated, and bioinformatics and egg-production association analyses were performed. Three SNPs (g.44069941G > A and g.44069889A > G in CALM1 and g.10742639C > T in DRD1) were detected in the exons and introns of CALM1 and DRD1 in 400 Taihang chickens. Among them, g.44069941G > A was significantly associated with Taihang chicken egg production on the 500th day (p < 0.05), whereas g.10742639C > T was significantly associated with the 300th day (p < 0.05). The expression levels of CALM1 and DRD1 in ovarian tissues of a high-yielding Taihang group were greater than in a low-yielding group (p < 0.05). The bioinformatics analysis revealed that the mutations influenced the mRNA secondary structures of CALM1 and DRD1. This study provides new insights into the potential effects of CALM1 and DRD1 polymorphisms on chicken egg production. The two SNPs g.44069941G > A and g.10742639C > T are potential molecular markers for improving the reproductive traits of Taihang chicken.

Genetic Markers as Risk Factors for the Development of Impulsive-Compulsive Behaviors in Patients with Parkinson's Disease Receiving Dopaminergic Therapy.

Impulsive–compulsive and related behavioral disorders (ICD) are drug-induced non-motor symptoms of Parkinson’s disease (PD). Recently research has focused on evaluating whether ICD could be predicted and managed using a pharmacogenetic approach based on dopaminergic therapies, which are the main risk factors. The aim of our study was to evaluate the role of candidate genes such as DBH, DRD2, MAOA, BDNF, COMT, SLC6A4, SLC6A3, ACE, DRD1 gene polymorphisms in the pathogenesis of ICD in PD. We compared patients with PD and ICD (n = 49), patients with PD without ICD (n = 36) and a healthy control group (n = 365). ICD was diagnosed using the QUIP questionnaires and specific diagnostic criteria for subtypes of ICD. Genotyping was conducted using a number of PCR techniques and SNaPshot. Statistical analysis was performed using WinPepi and APSampler v3.6 software. PCA testing was conducted using RStudio software v1.4.1106-5. The following substitutions showed statistically significant correlations with PD and ICD: DBH (rs2097629, rs1611115), DRD2 (rs6275, rs12364283, rs1076560), ACE (rs4646994), DRD1 (rs686), BDNF (rs6265), these associations are novel in Russian PD patients. Our findings suggest that polymorphisms in DBH, BDNF, DRD2, ACE genes in Russian subjects are associated with an increased risk of ICD development.

Analysis of Association Between the Effects of Methylphenidate and DRD4 Gene Polymorphisms in Patients with Attention Deficit Hyperactivity Disorder

Background: Drug treatment is one of the most important treatments for attention deficit hyperactivity disorder (ADHD). The DRD4 gene is a transporter and receptor coding gene of dopamine and is one of the most important genes under investigation in the disorder and etiology of ADHD. In this study, the association between rs3758653 C/T and VNTR exon 3 repetition polymorphisms of the DRD4 gene and the effects of methylphenidate were investigated in patients with ADHD disorder consuming methylphenidate. Methods: The descriptive-analytical study was performed on 122 patients (5 - 18 years old) with ADHD who were treated with methylphenidate. DNA was extracted using salting out method. Subsequently, the rs3758653 polymorphism in the 5'UTR region of DRD4 gene was genotyped by PCR-RFLP method, and the VNTR fragment in exon III of DRD4 gene was investigated by electrophoresis gel on acrylamide gel method. After eight weeks from the start of drug treatment with methylphenidate, the intensity of symptoms was evaluated using the Conners scale. Finally, all data from questionnaires and information that were resulted from laboratory findings were analyzed using ANOVA and repeated measure analysis. Results: Of the 122 patients under study, 15 patients (12.3%) were responded to the drug treatment, and 107 patients (87.7%) were not responded. The significant differences were not revealed in genotype, and allele frequencies of between rs3758653 (C/T) and exon III 3'VNTR repeats polymorphisms of the DRD4 gene and responder and non-responder of ADHD groups to the drug treatment. Conclusions: The results showed that the reduction of ADHD symptoms with drug treatment is not related to DRD4 sub-types in patients with ADHD.

A comprehensive in silico investigation into the nsSNPs of Drd2 gene predicts significant functional consequences in dopamine signaling and pharmacotherapy

DRD2 is a neuronal cell surface protein involved in brain development and function. Variations in the Drd2 gene have clinical significance since DRD2 is a pharmacotherapeutic target for treating psychiatric disorders like ADHD and schizophrenia. Despite numerous studies on the disease association of single nucleotide polymorphisms (SNPs) in the intronic regions, investigation into the coding regions is surprisingly limited. In this study, we aimed at identifying potential functionally and pharmaco-therapeutically deleterious non-synonymous SNPs of Drd2. A wide array of bioinformatics tools was used to evaluate the impact of nsSNPs on protein structure and functionality. Out of 260 nsSNPs retrieved from the dbSNP database, initially 9 were predicted as deleterious by 15 tools. Upon further assessment of their domain association, conservation profile, homology models and inter-atomic interaction, the mutant F389V was considered as the most impactful. In-depth analysis of F389V through Molecular Docking and Dynamics Simulation revealed a decline in affinity for its native agonist dopamine and an increase in affinity for the antipsychotic drug risperidone. Remarkable alterations in binding interactions and stability of the protein–ligand complex in simulated physiological conditions were also noted. These findings will improve our understanding of the consequence of nsSNPs in disease-susceptibility and therapeutic efficacy.

Genetically-predicted prefrontal DRD4 gene expression modulates differentiated brain responses to food cues in adolescent girls and boys

The dopamine receptor 4 (DRD4) in the prefrontal cortex (PFC) acts to modulate behaviours including cognitive control and motivation, and has been implicated in behavioral inhibition and responsivity to food cues. Adolescence is a sensitive period for the development of habitual eating behaviors and obesity risk, with potential mediation by development of the PFC. We previously found that genetic variations influencing DRD4 function or expression were associated with measures of laboratory and real-world eating behavior in girls and boys. Here we investigated brain responses to high energy–density (ED) and low-ED food cues using an fMRI task conducted in the satiated state. We used the gene-based association method PrediXcan to estimate tissue-specific DRD4 gene expression in prefrontal brain areas from individual genotypes. Among girls, those with lower vs. higher predicted prefrontal DRD4 expression showed lesser activation to high-ED and low-ED vs. non-food cues in a distributed network of regions implicated in attention and sensorimotor processing including middle frontal gyrus, and lesser activation to low-ED vs non-food cues in key regions implicated in valuation including orbitofrontal cortex and ventromedial PFC. In contrast, males with lower vs. higher predicted prefrontal DRD4 expression showed minimal differences in food cue response, namely relatively greater activation to high-ED and low-ED vs. non-food cues in the inferior parietal lobule. Our data suggest sex-specific effects of prefrontal DRD4 on brain food responsiveness in adolescence, with modulation of distributed regions relevant to cognitive control and motivation observable in female adolescents.

A next generation sequencing gene panel for use in the diagnosis of anorexia nervosa.

The aim of this study was to increase knowledge of genes associated with anorexia nervosa (AN) and their diagnostic offer, using a next generation sequencing (NGS) panel for the identification of genetic variants. The rationale underlying this test is that we first analyze the genes associated with syndromic forms of AN, then genes that were found to carry rare variants in AN patients who had undergone segregation analysis, and finally candidate genes intervening in the same molecular pathways or identified by GWAS or in mouse models. We developed an NGS gene panel and used it to screen 68 Italian AN patients (63 females, 5 males). The panel included 162 genes. Family segregation study was conducted on available relatives of probands who reported significant genetic variants. In our analysis, we found potentially deleterious variants in 2 genes (PDE11A and SLC25A13) associated with syndromic forms of anorexia and predicted deleterious variants in the following 12 genes: CD36, CACNA1C, DRD4, EPHX2, ESR1, GRIN2A, GRIN3B, LRP2, NPY4R, PTGS2, PTPN22 and SGPP2. Furthermore, by Sanger sequencing of the promoter region of NNAT, we confirmed the involvement of this gene in the pathogenesis of AN. Family segregation studies further strengthened the possible causative role of CACNA1C, DRD4, GRIN2A, PTGS2, SGPP2, SLC25A13 and NNAT genes in AN etiology. The major finding of our study is the confirmation of the involvement of the NNAT gene in the pathogenesis of AN; furthermore, this study suggests that NGS-based testing can play an important role in the diagnostic evaluation of AN, excluding syndromic forms and increasing knowledge of the genetic etiology of AN. Level I, experimental study.

Chronic pain and delinquency partially explain the effect of the DRD4 gene polymorphism on adult substance use

ABSTRACT Background: The dopamine receptor D4 [DRD4] has been reported to be associated with substance use. Yet, the roles that health conditions and behaviors may play in such association are understudied. Objective: This longitudinal study investigated the potential mediation effects of chronic pain and delinquency in adolescence on the association between the DRD4 2-repeat allele and substance use in adulthood. Sex, witnessing violence, and experiencing violence were also examined as potential moderators for the mediation pathways. Methods: We used the restricted and candidate gene data from the National Longitudinal Study of Adolescent to Adult Health (Waves I–IV) to conduct secondary analysis (N = 8,671; 47% male). A two-step approach was adopted to examine the mediation effects regarding four substance use outcomes in adulthood: number of lifetime alcohol use disorder symptoms, lifetime regular smoker status, past-month smoking, and lifetime “pain killer” misuse. The moderation effects were investigated using stratification and permutation. Results: The DRD4 2-repeat allele was associated with all adulthood substance use outcomes through adolescent chronic pain and delinquency (AORs/IRR range 1.08–3.78; all ps<0.01). The association between delinquency and smoking was higher among females. The association between delinquency and substance use was lower among the participants who witnessed violence in adolescence. Conclusions: This study identified modifiable mediators underlying the association between the DRD4 2-repeat allele and substance use behaviors, concluding that chronic pain and delinquency partially explain the effect of the DRD4 gene polymorphism on adult substance use.

Association of polymorphic variants of genes &lt;i&gt;(HTR2A, MTNR1A, MTNR1B, CLOCK, DRD2)&lt;/i&gt; and insomnia in alcohol dependence syndrome

The majority of patients with alcohol dependence syndrome suffer from sleep disorders, particularly insomnia, associated with a number of critical clinical aspects, increased suicide risk, anxiety and depression. The authors of relevant publications indicate associations between polymorphic melatonin genes and melatonin metabolism and symptoms of sleep disorders. However, the literature review failed to reveal any studies on the role of genetic polymorphism of circadian rhythm regulators in sleep disorders in patients with alcohol dependence.Objective: to determine the associations of polymorphic variants of genes HTR2A, MTNR1A, MTNR1B, CLOCK, DRD2 with sleep disorders risk in alcohol dependence syndrome.Patients and methods. 307 patients with alcohol dependence syndrome were screened, including 61 women (21%) and 246 (79%) men (mean age – 41.92±7.9 years). The presence and severity of sleep disorders were assessed by the Insomnia Severity Index. In addition, 10 ml of venous blood sample was obtained from all participants. Genotyping of single nucleotide variants of HTR2A (rs6313), MTNR1A (rs34532313), MTNR1B (rs10830963), CLOCK (rs1801260), DRD2 (rs1800497) genes was performed using real-time polymerase chain reaction. Statistical analysis of the data was conducted using parametric and nonparametric methods.Results and discussion. The carriage of the *G allele of the polymorphic variant of the MTNR1B (rs10830963) gene, and its genotypes are associated with a greater risk of insomnia than the carriage of *С/*С genotype. The carriage of the *С allele of the polymorphic variant of the CLOCK (rs1801260) gene, as well as the *С/*Т genotype, are associated with the presence of sleep disorders. No associations between polymorphic variants of the HTR2A (rs6313), DRD2 (rs1800497) genes and insomnia risk were detected in patients with alcohol dependence syndrome.Conclusion. The found associations reveal prospects for future research on melatonin's role in the pathophysiology of sleep disorders in patients with alcohol dependence and pathogenetic therapy for insomnia.

Alleles Frequency and Polymorphic Genes Genotypes Associated with Alcoholism in Kazakh Population

Background: There is a category of people with a congenial predisposition to alcohol abuse among the total population. The identification of such persons by molecular genetic diagnostics and the implementation of appropriate preventive measures can significantly reduce the incidence of alcoholism. Objectives: This research aimed to study the genetic foundations of alcohol dependence development in Kazakhs based on the analysis of population frequencies of polymorphic variants of predisposition to alcoholism genes. Materials and Methods: The material for the research was the DNA recovered from the peripheral blood of the recruited control group population, which was represented by 1,800 conditionally healthy individuals of Kazakh nationality. Isolated DNA samples were genotyped by PCR. The data was calculated and analyzed using HWEtest function of PLINK software. Conclusions: Kazakhs take an intermediate position between the previously studied European and Asian populations by allele frequencies of nine polymorphic variants of ADH1B (rs2066701, rs1789891), ADH1C (rs1693425, rs698), HTR2C (rs6318), ALDH2 (rs671), CADM2 (rs9841829), KLB (rs11940694), DRD2 (rs1076560) genes. Possible markers of an increased risk of alcoholism development in Kazakhs are G alleles of polymorphic loci rs2066701 of the ADH1B gene and rs671 of the ALDH2 gene, and the protective effect is possible in the presence of A alleles rs2066701 of the ADH1B gene and rs671 of the ALDH2 gene.