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Background: Regular therapy for schizophrenia includes maintenance antipsychotic treatment. Unfortunately, antipsychotics also have a spectrum of side effects, including metabolic, endocrine, cardiovascular, and movement disorders. One of the common side effects of these drugs is hyperprolactinemia (HPRL) [1]. This side effect is attributed to blockade of dopamine D2 receptors on the membranes of lactotroph cells within the pituitary gland. Certain antipsychotic drugs, e.g. risperidone, are more likely to induce HPRL because of relative accumulation within the adenohypophysis. The strong prolactin-elevating effect of risperidone reflects its relatively high blood/brain concentration ratio, a consequence of it being a substrate for the p-glycoprotein (P-gp, also known as ABCB1) pump [2]. Therefore, P-gp genotypes with altered functional activity might influence the potential of risperidone to cause HPRL as the changed blood/brain concentration ratio would lead to an altered vulnerability for CNS side effects like parkinsonism. Such side effects are expected to make dose adaptations necessary, which would also decrease exposure of lactrotroph dopamine D2 receptors. Aims: The present study aimed to investigate the influence of polymorphisms of the P-glycoprotein gene (ABCB1 gene) on the prevalence of antipsychotic-induced hyperprolactinemia in patients with schizophrenia. Methods: We studied the association between polymorphisms of the P-gp gene (ABCB1 gene) and antipsychotic drug-induced hyperprolactinemia in patients with schizophrenia from Siberia. Evaluation of serum prolactin was performed by ELISA using reagents set PRL Test System (USA). Genotyping was carried out on 8 polymorphic variants of the P-glycoprotein gene (rs1045642, rs2032582, rs4148739, rs28401781, rs2235040, rs9282564, rs2235015, and rs2032583). Associations between HPRL and polymorphisms of P-gp gene were established using logistic regression accounting for covariates (age, sex, duration of the disease, and CPZeq). An additive genetic model was tested and the analysis was carried out both in the total sample and in subgroups stratified by the use of risperidone/paliperidone (N = 76) or sulpiride/amisulpride (N = 13). Bonferroni correction was applied assuming 5 independent tests estimated via the correlation between the SNPs. Results: 446 Russian patients with schizophrenia were examined, including 225 women and 221 men [3]. The average age of patients was 42.1 ± 1.4 years. No statistically significant associations were obtained in the total sample after correction for multiple-testing. However, the rs2032582 variant appeared to be protective against HPRL in the subgroup of patients using risperidone or paliperidone (OR = 0.17, 95% CI = 0.04–0.79, adjusted p = 0.041). Discussion: Our finding supports the hypothesis that a variant of P-gp gene may influence the likelihood of inducing HPRL in patients using risperidone or paliperidone (i.e. 9-hydroxy-risperidone). This may be related to affecting the blood/brain concentration ratio of the risperidone moiety. In the total sample the association was significant but did not survive correction for multiple testing. Moreover, another variant, rs4148739, was associated to a larger extent than rs2032582. Hence, the variant may affect the affinity of the risperidone moiety specifically without having consequences for the binding and transport of other antipsychotic drugs. Conclusion: Rs2032582 of the P-gp is negatively associated with risperidone/paliperidone-induced HPRL, but not with HPRL induced by other antipsychotic drugs. References [1] Peuskens, J., Pani, L., Detraux, J., De Hert, M., 2014. The effects of novel and newly approved antipsychotics on serum prolactin levels: a comprehensive review. CNS Drugs 28, 421–453. [2] Ejsing, T., Pedersen, A., Linnet, K., 2005. P-glycoprotein interaction with risperidone and 9-OH-risperidone studied in vitro, in knock-out mice and in drug-drug interaction experiments. Hum Psychopharmacol 20, 493–500. [3] Ivanova, S.A., Osmanova, D.Z., Freidin, M.B., Fedorenko, O.Y., Boiko, A.S., Pozhidaev, I.V., Semke, A.V., Bokhan, N.A., Agarkov, A.A., Wilffert, B., Loonen, A.J.M., 2017. Identification of 5-hydroxytryptamine receptor gene polymorphisms modulating hyperprolactinaemia in antipsychotic drug-treated patients with schizophrenia. World J Biol Psychiatry 18, 239–246. Keywords: Schizophrenia: clinical Pharmacokinetics Neuroendocrinology

Predictive genetic model for levodopa-induced dyskinesia in patients with Parkinson's disease S.A. Ivanova(1), V.M. Alifirova(2), M.B. Freidin(3), I.V. Pozhidaev(4), O.Y. Fedorenko(4), N.A. Bokhan(4), I.A. Zhukova(5), N.G. Zhukova(5), B. Wilffert(6), A.J.M. Loonen(6) (1)Mental Health Research Institute, Molecular Genetics and Biochemistry Laboratory, Tomsk, Russia (2)Siberian State Medical University, Department of Neurology and Neurosurgery, Tomk, Russia (3)Tomsk National Research Medical Center of the Russian Academy of Sciences, Research Institute of Medical Genetics, Tomsk, Russia (4)Tomsk National Research Medical Center of the Russian Academy of Sciences, Mental Health Research Institute, Tomsk, Russia (5)Siberian State Medical University, Department of Neurology and Neurosurgery, Tomsk, Russia (6)University of Groningen, Groningen Research Institute of Pharmacy, Groningen, The Netherlands Parkinson's disease (PD), a common neurodegenerative disorder caused by the loss of the dopaminergic input to the basal ganglia, is commonly treated with levodopa (L-DOPA). The use of this drug, however, is severely limited by adverse effects. Levodopa-induced dyskinesia (LID) is one of these and characterized by involuntary muscle movements that occur as a consequence of chronic levodopa treatment. LID is a substantial barrier to effective symptomatic management of PD as up to 45% of L-DOPA users develop LID within 5 years [1]. Clinical heterogeneity of LID suggests a significant role of endogenous factors in determining their prevalence. Some evidences suggest a relationship between LID and specific genetic variants, such as polymorphisms in the genes controlling enzymes responsible for drug and monoamine metabolism, neurotransmitter receptors and proteins involved in oxidative stress or antioxidant function [2–4]. Objective: To investigate a contribution of polymorphic variants of neurotransmitter receptors and cytochrome genes in the development of LID in PD patients. Methods: A total of 212 PD patients who received L-DOPA therapy were studied. Dyskinesia was assessed by using the Abnormal Involuntary Movement Scale (AIMS). DNA extraction and genotyping were conducted according to standard protocols and blind to the clinical status of the subjects. Genotyping was carried out for 72 SNPs of DRD1, DRD2, DRD2/ANKK1, DRD3, DRD4, HTR2C, HTR3A, HTR3B, HTR6, HTR2A, HTR1A, HTR1B, CYP1A2*1F, CYP2D6*3, CYP2D6*4, CYP2C19*3, CYP2C19*17, CYP2C19*2, and GSTP1 genes using MassARRAY® Analyzer 4 (Agena Bioscience™) and the set SEQUENOM Consumables iPLEX Gold 384. Discriminant analysis and receiver operating curve (ROC)-analysis were carried out to build a genetic predictive model for dyskinesia. Results: Group of PD patients consists of 149 females and 83 males (age ranging from 40 to 86 years, average age 68.7 ± 7.6 years). The mean age of onset is 60.04 ± 9.46 years, average disease duration is 9.79 ± 5.57 years. Dyskinesia was reported in 57 (26.9%) patients. The best discriminant model was obtained with the following predictors: rs11721264, rs165774, rs3758653, rs4245147, rs6313, rs1364043, rs2734849, rs324035, rs6311, rs11246226 and rs4244285. These polymorphisms are localized in the following genes: DRD3 (rs11721264, rs324035), DRD4 (rs3758653, rs11246226), DRD2 (rs4245147, rs2734849), HTR2A (rs6313, rs6311), HTR1A (rs1364043). The discriminant model using this set of SNPs gives the error of classification about 13% and the AUC 0.795. Depending on the anticipated frequency of LID, positive and negative predictor values varied between 0.745–0.834 and 0.864–0.916, respectively. We hypothesized in our previous studies that the pathological basis of LID might be degeneration of indirect pathway medium spiny neurons [5]. These indirect pathway medium spiny neurons carry type 2 family dopamine receptors (DRD2, DRD3, DRD4), and HTR2A receptors. Moreover, dopamine release may be promoted by inhibiting serotonergic neurotransmission. Hence, the current findings are well in line with this hypothesis. Conclusion: The resulting panel of 11 SNPs provides a sufficiently high accuracy of LID prediction. The use of this panel in a prospective study will clarify the prospects for its application in clinical practice for predicting risk of LID in patients with PD. References [1] Rascol, O., Brooks, D.J., Korczyn, A.D., et al., 2000. Study Group: A five–year study of the incidence of dyskinesia in patients with early Parkinson's disease who were treated with ropinirole or L–DOPA. N Engl J Med 342, 1484–1491. [2] Ivanova, S.A., Fedorenko, O.Yu., Freidin, M.B., et al., 2016. Dissimilar mechanistic background of peripheral and orofacial hyperkinesia in patients with Parkinson's disease and levodopa-induced dyskinesia. Physiology and Pharmacology 19, 216–221. [3] Kaplan, N., Vituri, A., Korczyn, A.D., et al., 2014. Sequence variants in SLC6A3, DRD2, and BDNF genes and time to levodopa-induced dyskinesias in Parkinson's disease. J Mol Neurosci 53 (2), 183–188. [4] Loonen, A.J.M., Ivanova, S.A., 2016. Role of 5-HT2C receptors in dyskinesia. International Journal of Pharmacy and Pharmaceutical Sciences 8 (1), 5–10. [5] Loonen, A.J., Ivanova, S.A., 2013. New insights into the mechanism of drug-induced dyskinesia. CNS Spectr 18, 15–20. Keywords: Genetics / Molecular genetics Parkinson's disease levodopa-induced dyskinesia

Dopamine receptors genes polymorphisms in Parkinson patients with levodopa-induced dyskinesia I. Pozhidaev(1), V.M. Alifirova(2), M.B. Freidin(3), I.A. Zhukova(2), O.Y. Fedorenko(1), D.Z. Osmanova(1), Y.S. Mironova(2), B. Wilffert(4), S.A. Ivanova(1), A.J.M. Loonen(5) (1)Mental Health Research Institute, Molecular Genetics and Biochemistry, Tomsk, Russia (2)Siberian State Medical University, Neurology and Neurosurgery, Tomsk, Russia (3)Research Institute for Medical Genetics, Laboratory of Population Genetics, Tomsk, Russia (4)Groningen Research Institute of Pharmacy, Pharmacotherapy and Clinical Pharmacology, Groningen, The Netherlands (5)Groningen Research Institute of Pharmacy, Pharmacotherapy in Psychiatric Patients, Groningen, The Netherlands Introduction: Long-term levodopa treatment of Parkinson's disease (PD) is frequently complicated by spontaneously occurring involuntary muscle movements called levodopa-induced dyskinesia (LID). LID are a substantial barrier to effective symptomatic management of Parkinson's disease (PD), as up to 45% of L-DOPA users develop LID within 5 years [1]. The exact pathological mechanism of this complication has not yet been elucidated. A lot of studies nowadays which approved complex genetic nature of LID. And these genes are involved not only for oxidative stress, but in drug metabolism too [2–4]. Objective: This study aimed to investigate a possible contribution of polymorphic variants of DRD1, DRD2, DRD2/ANKK1, DRD3, DRD4 genes in the development of LID in PD patients. Methods: 212 patients with Parkinson's disease on levodopa therapy were investigated. Dyskinesia was measured by using Abnormal Involuntary Movement Scale (AIMS). DNA extraction and fluorogenic 5′-exonuclease TaqMan genotyping assays were conducted according to standard protocols and blind to clinical status of the subjects. Genotyping was carried out on 28 SNPs of dopamine receptors (rs4532, rs936461, rs6275, rs1801028, rs4245147, rs134655, rs6277, rs1076560, rs2283265, rs179997, rs6279, rs1076562, rs2734842, rs2734849, rs11721264, rs167770, rs3773678, rs963468, rs7633291, rs2134655, rs9817063, rs324035, rs1800828, rs167771, rs6280, rs1587756, rs3758653, rs11246226) on the MassARRAY® Analyzer 4 (Agena Bioscience™) using the set SEQUENOM Consumables iPLEX Gold 384. SPSS software was used for statistical analysis. Statistical significance of the association testing was established using permutations. P-value

Association of polymorphism in the dopamine receptors and transporter genes with hyperprolactinemia in patients with schizophrenia D. Osmanova(1), A.S. Boiko(1), O.Y. Fedorenko(1), I.V. Pozhidaev(1), M.B. Freidin(2), E.G. Kornetova(3), S.A. Ivanova(1), B. Wilffert(4), A.J.M. Loonen(5) (1)Mental Health Research Institute- Tomsk NRMC, Laboratory of Molecular Genetics and Biochemistry, Tomsk, Russia (2)Research Institute of Medical Genetics, Tomsk NRMC, Laboratory of Population Genetics, Tomsk, Russia (3)Mental Health Research Institute- Tomsk NRMC, Department of Clinical and Social Psychiatry and Addiction, Tomsk, Russia (4)Groningen Research Institute of Pharmacy, Pharmacotherapy and Clinical Pharmacology, Groningen, The Netherlands (5)Groningen Research Institute of Pharmacy, Pharmacotherapy in Psychiatric Patients, Groningen, The Netherlands Background: Long-term antipsychotic drug use remains the mainstay of treatment for patients with schizophrenia. However, pharmacotherapy with these drugs is complicated by several troublesome side effects, including hyperprolactinemia (HP). Prolactin secretion is persistently inhibited by dopamine, and antipsychotic drugs are believed to increase prolactin release by blocking dopamine receptors in the pituitary gland. Genetic factors play an important role in the development of antipsychotic induced HP [1,2]. Genes coding for dopamine receptors and transporters are considered to be responsible for HP in schizophrenia [3]. The present study aimed to investigate the role of polymorphisms of the dopamine receptors and transporters genes (DRD1, DRD2, SLC6A3) in the pathogenesis of antipsychotic-related HP in patients with schizophrenia. Methods: 431 Russian patients with schizophrenia were examined. The average age of patients was 42.1 ± 1.4 years. Evaluation of serum prolactin level was performed by ELISA using reagents set PRL Test System (USA). Genotyping was carried out on 17 polymorphic variants of the dopamine receptors and transporters genes DRD1 (rs4532, rs936461), DRD2 (rs4245147, rs6279, rs2734842) and SLC6A3 (rs3756450, rs2550956, rs6347, rs2617605, rs3863145, rs250686, rs464049, rs4975646, rs1048953, rs11133767, rs27048, rs40184). The SPSS software was used for statistical analysis. The Hardy-Weinberg equilibrium (HWE) of genotypic frequencies was tested by the chi-square test. Results: We studied the association between HP and a set of SNPs from DRD1, DRD2 receptor genes and neurotransmitter transporter SLC6A3 in patients from Siberia with a clinical diagnosis of schizophrenia who were treated with classical and/or atypical antipsychotic drugs. All patients with schizophrenia were divided into two groups: those with and without HP. Physiological normal results for the serum prolactin levels are less than 20 ng/ml in men, and less than 25 ng/ml in women. Statistically significant result was obtained for polymorphic variant rs2550956 of the gene SLC6A3 (χ2 = 9.992; p = 0.007), which suggests its involvement in the development of HP. The heterozygous genotype TC of rs2550956 was significantly less common in patients with elevated levels of prolactin and it presumably has protective properties (OR 0.54; 95% CI: 0.36–0.81). We did not find any statistically significant associations for other polymorphisms DRD1 (rs4532, rs936461), DRD2 (rs4245147, rs6279, rs2734842) and SLC6A3 (rs3756450, rs6347, rs2617605, rs3863145, rs250686, rs464049, rs4975646, rs1048953, rs11133767, rs27048, rs40184). The group of dopamine receptors is heterogeneous and only some of them participate in the formation of psychotic symptoms and, accordingly, in the antipsychotic action of neuroleptics. The effect of neuroleptics on other groups of dopamine receptors leads to the development of different side effects including extrapyramidal disorders [4], and their role is extremely low in the formation of the actual therapeutic response. Conclusion: Our results indicate that genetic variants of SLC6A3 may have functional consequences on the modulation of prolactin secretion. Neurotransmitter systems are involved in the mechanisms of action of antipsychotic drugs; therefore, a further search for genetic markers associated with the development of antipsychotic-related hyperprolactinemia in schizophrenic patients is needed. References [1] Ivanova, S.A., Osmanova, D.Z., Boiko, A.S., Pozhidaev, I.V., Freidin, M.B., Fedorenko, O.Y., Semke, A.V., Bokhan, N.A., Kornetova, E.G., Rakhmazova, L.D., Wilffert, B., Loonen, A.J., 2016. Prolactin gene polymorphism (-1149G/T) is associated with hyperprolactinemia in patients with schizophrenia treated with antipsychotics. Schizophrenia Research Oct 21, pii: S0920-9964 (16)30473-X. doi: 10.1016/j.schres.2016.10.029. [2] Ivanova, S.A., Osmanova, D.Z., Freidin, M.B., Fedorenko, O.Y., Boiko, A.S., Pozhidaev, I.V., Semke, A.V., Bokhan, N.A., Agarkov, A.A., Wilffert, B., Loonen, A.J., 2017. Identification of 5-hydroxytryptamine receptor gene polymorphisms modulating hyperprolactinaemia in antipsychotic drug-treated patients with schizophrenia. World J Biol Psychiatry 18 (3), 239–246. [3] Miura, I., Zhang, J.P., Hagi, K., Lencz, T., Kane, J.M., Yabe, H., Malhotra, A.K., Correll, C.U., 2016. Variants in the DRD2 locus and antipsychotic-related prolactin levels: A meta-analysis. Psychoneuroendocrinology 72, 1–10. [4] Al Hadithy, A.F.Y., Ivanova, S.A., Pechlivanoglou, P., Semke, A., Fedorenko, O., Kornetova, E., Ryadovaya, L., Brouwers, J.R.B.J., Wilffert, B., Bruggeman, R., Loonen, A.J.M., 2009. Tardive dyskinesia and DRD3, HTR2A and HTR2C gene polymorphisms in Russian psychiatric inpatients from Siberia. Progress in NeuroPsychopharmacology and Biological Psychiatry 33, 475–481. Keywords: Dopamine Genetics / Molecular genetics Schizophrenia: basic

Background: Antipsychotics have been used for more than 50 years in the treatment of schizophrenia and many other psychiatric disorders. Schizophrenic patients have to take antipsychotic medication for a long time, often throughout the life [1]. Hyper prolactinemia in these patients is a common and serious side effect of therapy with atypical antipsychotics. Genes coding for serotonin receptors are considered as candidate genes responsible for the particular antipsychotic effects of neuroleptics [2]. The present study aimed to investigate the role of polymorphisms of the serotonin receptors genes (HTR1A, HTR1B, HTR2A, HTR2C, HTR3A, HTR3B, HTR6) in the pathogenesis of antipsychotic-induced hyperprolactinemia in patients with schizophrenia. Methods: 446 Russian patients with schizophrenia were examined, including 225 women and 221 men. The average age of patients was 42.1±1.4 years. Evaluation of serum prolactin performed by ELISA using reagents set PRL Test System (USA). Genotyping was carried out on 29 polymorphic variants of the serotonin receptor genes HTR1A (rs6295, rs1364043, rs10042486, rs1800042, rs749099), HTR1B (rs6298, rs6296, rs130058), HTR2A (rs6311, rs6313, rs6314, rs7997012, rs1928040, rs9316233, rs2224721, rs6312), HTR2C (rs6318, rs5946189, rs569959, rs17326429, rs4911871, rs3813929, rs1801412, rs12858300), HTR3A (rs1062613, rs33940208, rs1176713), HTR3B (rs1176744) and HTR6 (rs1805054). The SPSS software was used for statistical analysis. The Hardy-Weinberg equilibrium (HWE) of genotypic frequencies was tested by the chi-square test. Results: We studied the association between polymorphisms of relevant 5-HT receptor genes and antipsychotic drug-induced hyperprolactinemia in patients with schizophrenia from Siberia. All patients with schizophrenia were divided into two groups: those with and without hyperprolactinemia. Statistically significant results were obtained for polymorphic variants of the genes rs6312 HTR2A (χ2 = 4.685; p = 0.030), rs12858300 HTR2C, rs569959 HTR2C, which suggests the participation of these polymorphic variants in the development of hyperprolactinemia. When men and women were studied separately, only rs569959 HTR2C (χ2 = 6.284; p = 0.043) in men reached the nominal significance threshold. This finding is probably related to the X-bound character of HTR2C (i.e., men are hemizygotes). Also, we found a statistically significant association rs12858300 HTR2C (χ2 = 9.429; p = 0.002) in the female group. We did not find statistically significant association for other polymorphisms HTR1A (rs6295, rs1364043, rs10042486, rs1800042, rs749099), HTR1B (rs6298, rs6296, rs130058), HTR2A (rs6311, rs6313, rs6314, rs7997012, rs1928040, rs9316233, rs2224721), HTR2C (rs6318, rs5946189, rs17326429, rs4911871, rs3813929, rs1801412), HTR3A (rs1062613, rs33940208, rs1176713), HTR3B (rs1176744) and HTR6 (rs1805054). Though hyperprolactinemia is primarily attributed to blockade of DRD2 in the pituitary gland, the secretion of prolactin is also modulated by 5-HT. The involvement of the HTR1A, HTR2A, HTR2C, and HTR3 in the serotonergic-induced prolactin response is well documented. Conclusion: Our results indicate that genetic variants of HTR2C may have functional consequences on the modulation of prolactin secretion. Further search for genetic markers associated with the development of side effects of neuroleptic therapy, will contribute to the development of effective methods of diagnosis, correction and treatment of disease, as well as of adherence of patients with mental disorders to psychotropic therapy.

Parkinson's disease (PD), a common neurodegenerative disorder caused by the loss of the dopaminergic input to the basal ganglia, is commonly treated with levodopa (L-DOPA). Use of this drug, however, is severely limited by the development of side effect. Levodopa-induced dyskinesias (LID) are involuntary muscle movements that occur as a consequence of chronic levodopa (L-DOPA) treatment. LID are a substantial barrier to effective symptomatic management of Parkinson's disease (PD), up to 45% of L-DOPA users develop LID within 5 years [1]. Clinical heterogeneity of LID suggests a significant role of endogenous factors in determining their prevalence. Some evidence suggest a relationship between LID and specific genetic changes, such as changes in the genes controlling enzymes responsible for drug and monoamine metabolism, neurotransmitter receptors and proteins involved in oxidative stress or antioxidant function [2-4]. Objective: To investigate contribution of polymorphic variants of CYP2D6 and COMT genes in the development of LID in PD patients. Methods: 212 patients with Parkinson's disease on levodopa therapy were investigated. Dyskinesias were estimated with use of Abnormal Involuntary Movement Scale (AIMS). DNA extraction and fluorogenic 5'-exonuclease TaqMan genotyping assays were conducted according to standard protocols and blind to the clinical status of the subjects. Genotyping was carried out on 2 SNPs of CYP2D6 (CYP2D6∗3, rs35742686; CYP2D6∗4, rs3892097) and 7 SNPs of COMT genes (rs4680, rs6269, rs4633, rs4818, rs769224, rs165774, rs174696). The SPSS software was used for statistical analysis. Results: Patients in our cohort demonstrated typical PD demographics, with a mean age of onset of 60.04±9.46 years, a mean disease duration of 9.79±5.57 years. Dyskinesias were reported in 57 (26.9%) patients. The distribution of genotypes of studied genes corresponded to the Hardy-Weinberg equilibrium. Association of polymorphisms in CYP2D6 gene with side effects was not revealed. We found that rs4680 polymorphism in COMT gene is significantly associated with LID (χ2 = 6.048, p = 0.049). Odds ratio for carriers of the genotype AA is 2.14 [95% CI: 1.11- 4.11], which indicates the predisposing effect of this genotype on the development of dyskinesias. Rs4680 is a functional SNP in genes encoding the catechol-O-methyltransferase enzyme, which catabolizes dopamine. A valine to methionine substitution at codon 158 of the COMT gene produces a Met variant that catabolizes dopamine up to four times slower than its Val counterpart. Conclusions: Polymorphisms in the COMT gene play significant role in the therapy response to L-DOPA as well as in various adverse effects. COMT is an extracellular enzyme which inactive variants increase the extracellular concentration of dopamine. This may increase the uptake of dopamine by indirect pathway MSN and therefore increase oxidative stress. We hypothesized that functional single nucleotide polymorphism rs4680 in COMT gene may result in a clinical phenotype contributing to an increased risk of LID. Thus, the polymorphism of gene possessing predisposing effects in development of levodopa induced dyskinesia in PD has been revealed that would allow predicting risk of development of movement disorders.