A. F. Y. Al Hadithy

Tardive dyskinesia and DRD3, HTR2A and HTR2C gene polymorphisms in Russian psychiatric inpatients from Siberia.

BACKGROUNDnPharmacogenetics of tardive dyskinesia and dopamine D3 (DRD3), serotonin 2A (HTR2A), and 2C (HTR2C) receptors has been examined in various populations, but not in Russians.nnnPURPOSEnTo investigate the association between orofaciolingual (TDof) and limb-truncal dyskinesias (TDlt) and Ser9Gly (DRD3), -1438G>A (HTR2A), and Cys23Ser (HTR2C) polymorphisms in Russian psychiatric inpatients from Tomsk, Siberia.nnnMETHODSnIn total, 146 subjects were included. Standard protocols were applied for genotyping. TDof and TDlt were assessed with AIMS items 1-4 and 5-7, respectively. Two-part model, logistic and log-normal regression analyses were applied to assess different variables (e.g., allele-carriership status, age, gender, and medication use).nnnRESULTSnTDlt, but not TDof, exhibited an association with Ser9Gly and Cys23Ser (with 9Gly and 23Ser alleles exhibiting opposite effects). However, -1438G>A was not associated with TDof and Dlt.nnnCONCLUSIONSnThis is the first pharmacogenetic report on tardive dyskinesia in Russians. Subject to further replication, our findings extend and support the available data.

The role of dopamine D3, 5-HT2A and 5-HT2C receptor variants as pharmacogenetic determinants in tardive dyskinesia in African-Caribbean patients under chronic antipsychotic treatment

Abstract Tardive dyskinesia (TD) is associated with polymorphisms of the dopamine D3, serotonin 2A and 2C receptors (DRD3, HTR2A and HTR2C, respectively). This study investigated the possible relationship between TD and the polymorphisms Ser9Gly (DRD3), 102T>C (HTR2A), −1438G>A(HTR2A) and Cys23Ser (HTR2C) in African-Caribbean inpatients. One hundred and twenty-six patients under chronic antipsychotic treatment were genotyped. The assessment of TD was carried out with the abnormal involuntary movement scale (AIMS). The relationships between the carriership of the least frequent alleles and the respective orofaciolingual dyskinesia (TDof) (sum of the items 1-4 of the AIMS), limb-truncal dyskinesia (TDlt) (sum of items 5-7 of the AIMS) and TD (sum of items 1-7 of the AIMS) were analyzed with ANCOVA, comparing means with age as a covariate and stratification for carriers and non-carriers of the mutations. In addition, we conducted pre-planned t-tests to compare AIMS values of carriers of the combinations of alleles versus the corresponding non-carriers. In the study population, females with 9Ser carriership exhibited higher AIMS values than non-carriers. Male subjects with 9Ser carriership in combination with 23Ser or −1438A carriership exhibited higher AIMS values. In male patients also, the combination of 23Ser and −1438A carriership increased TD. The study clearly shows that the African-Carribean population differs from the Caucasian population with regard to the association of TD with the polymorphisms studied and suggests that the association of TD with the studied polymorphisms of the 5-HT2C and probably of the 5-HT2A receptor are the result of a changed susceptibility of the patients, independent of the action of the antipsychotics on these receptors.

NMDA receptor genotypes associated with the vulnerability to develop dyskinesia

Dyskinesias are involuntary muscle movements that occur spontaneously in Huntingtons disease (HD) and after long-term treatments for Parkinsons disease (levodopa-induced dyskinesia; LID) or for schizophrenia (tardive dyskinesia, TD). Previous studies suggested that dyskinesias in these three conditions originate from different neuronal pathways that converge on overstimulation of the motor cortex. We hypothesized that the same variants of the N-methyl-D-aspartate receptor gene that were previously associated with the age of dyskinesia onset in HD were also associated with the vulnerability for TD and not LID. Genotyping patients with LID and TD revealed, however, that these two variants were dose-dependently associated with susceptibility to LID, but not TD. This suggested that LID, TD and HD might arise from the same neuronal pathways, but TD results from a different mechanism.

Missense polymorphisms in three oxidative-stress enzymes (GSTP1, SOD2, and GPX1) and dyskinesias in Russian psychiatric inpatients from Siberia

Neuronal degeneration due to oxidative stress (OS) has been proposed as a mechanism for tardive dyskinesia (TD) pathogenesis. Cellular defense mechanisms against OS may involve detoxification enzymes (e.g., glutathione peroxidase‐1, GPX1; superoxide dismutase‐2, SOD2 [also commonly known as MnSOD]; and glutathione S‐transferase P1, GSTP1). Several pharmacogenetic studies have examined TD and OS in different ethnic groups, but not in Russians. Here we report the association between orofaciolingual (TDof) and limb‐truncal dyskinesias (TDlt) and polymorphisms of GSTP1 (Ile105Val), MnSOD (Ala‐9Val), and GPX1 (Pro197Leu) genes in 146 Russian inpatients from Siberia. We applied AIMS instrument to rate dyskinesias. Two‐part model analyses, logistic and multivariate parametric regressions were applied to assess the effects of different variables (e.g., genotype, age, gender, and medication use). Our analyses do not suggest that Pro197Leu (GPX1) is associated with TD. However, our analyses suggest that the 105Val‐allele of Ile105Val (GSTP1) may be associated with a lower risk and a severity of TDof and TDlt and that Ile105Val pharmacogenetics may be different in Slavonic Caucasians from that in American Caucasians. Furthermore, we find evidence for an association between Ala‐9Val (MnSOD) and TDof, but not TDlt. Subject to further replication, our findings extend the available knowledge on the pharmacogenetics of TD and oxidative stress. Copyright

Stability of sildenafil (Revatio®) dilutions in dextrose 5%

Dear Editor, With great interest we read the paper of Fraisse et al. [1] in which the authors document the intravenous (i.v.) use of sildenafil in paediatric patients with congenital heart disease and pulmonary hypertension. The findings of the authors are important, since the commercially available sildenafil solution for injection (Revatio 0.8 mg/ml, 50 ml) is only licensed for administration as a bolus injection and unwanted excessive hypotensive effects may occur after administration of a bolus dose. Recently, we administered sildenafil intravenously to two paediatric patients at the Erasmus MC Sophia Children’s Hospital. One of the children (girl, age 4.5 years, 17 kg) was treated with sildenafil orally for 16 days (3 mg/ kg daily) and subsequently with sildenafil i.v. bolus injections for 27 days (0.5–1.0 mg/kg three times daily). Bolus sildenafil injections resulted in reductions in arterial systolic and diastolic pressures of approximately 20%. The second child (boy, neonate, age 23 days, 3.0 kg) received one bolus sildenafil i.v. dose of 0.2 mg/kg, after which arterial systolic and diastolic pressures dropped also by approximately 20%. Thereafter, a sildenafil continuous infusion was started with a loading dose of 0.4 mg/kg in 3 h and maintenance dose of 1.9 mg/kg daily for 5 days in total. During the continuous i.v. infusion, no marked fluctuations in arterial systolic and diastolic pressures were observed. As described by Fraisse et al. [1], maintenance infusions of sildenafil may have clear advantages. However, in order to correctly administer continuous i.v. (maintenance) infusions of sildenafil to paediatric patients, the commercially available product may frequently require dilution prior to administration. The current authorized version of the summary of product characteristics of Revatio , and major handbooks such as those by Trissel [2] and Bing [3], as well as other pharmaceutical literature sources, do not provide information on how sildenafil dilutions for continuous i.v. administration should be prepared and stored. Also Fraisse et al. [1] did not explicitly state how the maintenance infusion should be prepared and stored. To address this issue, we studied the stability of two Revatio dilutions (0.067 and 0.667 mg/ml) in dextrose 5%, which is the diluent of choice in most neonatal and paediatric intensive care units. Both dilutions were stored in 50-ml Luer-Lok polypropylene syringes (BD Plastipak, Spain) at ambient room temperature (20–25 C) and at 37 C (laboratory incubator) for 24 h and 7 days. Thereafter, and after performing a system suitability test and the preparation of two three-point aqueous calibration curves (concentration ranges are 0.04–0.08 and 0.4–0.8 mg/ml), we determined the concentration of sildenafil in both dilutions using a validated HPLC method (C18 ODS-3 5-lm column, 50:50 v/v acetonitrile/ammonium acetate 10 mM mobile phase, detection at 292 nm; Shimadzu LC20 diode array detector and HPLC system), and the coefficients of variation for repeatability, reproducibility and accuracy were found to be 0.1, 1.7 and 1.8%, respectively. The system suitability test complied with the general requirements of the United States Pharmacopeia [tailing and capacity (k0) factors were about 0.97 and 3.3, respectively]. The calibration curves exhibited satisfactory correlation coefficient and goodness-of-fit values (both C0.999). Measurement of the sildenafil concentrations in both dilutions at the end of the incubation periods (1 and 7 days) suggested no marked degradation at either temperature (room temperature or 37 C), since all of the concentrations measured were higher than 95.4% (percent of nominal concentration at t = 0 h) and since the peak-purity index was 1.000 in all of the measurements, indicating the absence of degradation products. Our findings therefore suggest that Revatio dilutions in dextrose 5% in the range 0.067–0.667 mg/ml are chemically stable for up to 1 week at room temperature (and hence clinically usable provided that antiseptic conditions are strictly applied during compounding). Our findings thus provide the pharmaceutical basis to enable administration of diluted sildenafil as a maintenance infusion to paediatric patients.

Polymorphisms of DRD2, DRD3, DRD4 and HTR2C genes in levodopa-induced dyskinesias in Parkinson's disease

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 Parkinsons 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 metabolism, neurotransmitter receptors, as well as proteins involved in oxidative stress or antioxidant function [2]. Our previous results showed that the susceptibility to LID was associated with two NMDA receptor (GRIN2A) variants [3]. Objective: To investigate contribution of polymorphic variants of HTR2C serotonin receptor gene and DRD2, DRD3 and DRD4 dopamine receptors genes in the development of LID in PD patients. Methods: 143 patients with Parkinsons disease were examined. Dyskinesias were estimated with use of Abnormal Involuntary Movement Scale (AIMS). Orofaciolingual LID (LIDof) and limb-truncal LID (LIDlt) were assessed with AIMS items 1-4 and 5-7, respectively. 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 23 polymorphic variants of DRD2, DRD3, DRD4 and HTR2C genes (rs6275, rs1800497, rs1799732, rs71653615, rs11721264, rs167770, rs3773678, rs963468, rs7633291, rs2134655, rs9817063, rs324035, rs1800828, rs167771, rs3758653, rs6318, rs5946189, rs569959, rs17326429, rs4911871, rs3813929, rs1801412, rs12858300). The softwares “R” and SPSS were used for statistical analysis. The Hardy-Weinberg equilibrium (HWE) of genotypic frequencies was tested by the chi-square test. For the SNPs in the X-chromosomal HTR2C gene, deviation from HWE was not calculated. Results: Associations of 5 polymorphisms with levodopainduced dyskinesias in patients with PD were revealed. Polymorphisms associated with orofaciolingual LID virtually did not overlap with polymorphisms associated with limb-truncal LID, indicating the different genetic basis of these phenotypes. Moreover, LIDof and LIDlt are associated with different genes polymorphisms. LIDof is associated with DRD4 (rs3758653) and HTR2C (rs4911871, rs5946189) genes polymorphisms whereas LIDlt is associated with only one of studied polymorphism. Polymorphisms of DRD3 gene (rs2134655, rs963468) are associated with severity of dyskinesia: rs2134655 - with orofaciolingual LID; rs963468 - with limb-truncal LID, but not with the fact of the presence of dyskinesia itself. Conclusions: Polymorphisms in the genes coding for neurotransmitter receptors play significant roles in the therapy response to L-DOPA as well as in various adverse effects. We hypothesised that single nucleotide polymorphisms in specific genes, particularly those coding for dopamine and serotonin receptors, may result in a clinical phenotype contributing to an increased risk of LID. Thus, the polymorphisms of genes possessing protective or predisposing effects in development of levodopa induced dyskinesia in PD have been revealed that would allow predicting risk of development of movement disorders.

P.3.a.006 Tardive dyskinesia, dehydroepiandrosterone sulfate and cytochrome P450c17α gene polymorphism in psychiatric inpatients

Tardive dyskinesia (TD) is a potentially irreversible antipsychoticinduced movement disorder with a prevalence of about 20-30% in psychiatric patients chronically exposed to antipsychotics. A wellknown theory states that TD is related to oxidative stress induced neurotoxicity. Dehydroepiandrosterone (DHEA) is an endogenous antioxidant with neuroprotective activity. The biosynthesis of DHEA depends upon the activity of cytochrome P450c17a (CYP17). The gene that encodes for CYP17 has a (T34C) single nucleotide polymorphism which enhances CYP17 transcription and expression. Objective: To test the hypothesis that carriership of a more active CYP17 variant would result in higher DHEA(S) levels and protect against neurotoxicity which results in orofaciolingual TD (TDof), limb-truncal TD (TDlt) or both (TDsum). Methods: TD was assessed cross-sectionally by the use of the Abnormal Involuntary Movement Scale (AIMS) in in 146 Caucasian psychiatric inpatients from Siberia. TDof and TDlt were assessed with AIMS items 1-4 and 5-7, respectively. The DHEAs levels were tested with aid of the DHEA-S ELISA Kit, (DRG International Inc.). DNA extraction and fluorogenic 5′-exonuclease TaqMan genotyping assays were conducted according to standard protocols and blind to the clinical status of the subjects [1]. The statistical software R was used for the calculations. For creating an overview of the clinical and demographic features of the study population, excel and the statistical SPSS software, release 17, for Windows were used. The deviation from the Hardy-Weinberg Equilibrium was tested by the chi-squared test for the Cyp17 polymorphisms. Results: In total 146 patient with clinical diagnosis of schizophrenia or schizotypal disorder (ICD-10: F20 and F21, respectively) were included of which 91 males and 55 females. Demographic and clinical details have been provided with elsewhere [1,2]. The genotype distribution in the total population and by gender shows that the female patients of this population are more often carrier of the Cyp17 CC genotype compared to male patients. The results of the logistic regression analysis of the influence of the Cyp17 T-allele and the level of DHEAS on the occurrence of TD, TDof and TDlt indicate that carriers of the Cyp17 genotype CC have a significant lower risk of developing TD compared to carriers of the Cyp17 genotypes TC or TT (p

Antipsychotic treatment response in caucasian patients : Association analysis of polymorphisms in 7 candidate genes in the group study

Background: The large variation in individual clinical responses to antipsychotic treatment hampers the management of psychotic disorders. Genetic factors are considered a main cause of this variation. Pharmacogenetics studies have demonstrated significant associations between several candidate genes (a.o. D2, D3, 5HTR2A and 5HTR2C, GRM3, COMT and MTHFR) and the response to antipsychotic drugs. The present study investigates the effect of 12 polymorphisms for an association with antipsychotic treatment response in patients with a psychotic disorder. Methods: 335 Caucasian patients with a non-affective psychotic disorder using antipsychotics were included. All patients participated in the longitudinal GROUP-study in The Netherlands. We genotyped 12 SNPs in 7 candidate genes (DRD2: TaqI-A, TaqI-D, -141-C, C957T; DRD3: Ser9Gly; HTR2A: 102-T/C, His452Tyr; HTR2C: Cys23Ser, -759-T/C; COMT: Val108/158Met; MTHFR: 677-C/T, GRM3: rs274622) using standard protocols. Polymorphisms were based on previous studies showing associations with treatment response. The Clinical Global Impression- Schizophrenia scale was cross-sectionally used to assess improvement in positive psychotic symptoms since the start of current antipsychotic treatment. Ordinal regression was used to test for an association between polymorphisms and improvement in positive symptoms. All polymorphisms were tested in an additive model, with minor allele dose as the dependent variable. Results: Ninety percent of the patients used atypical antipsychotics, with olanzapine (31%) and risperidone (29%) being the most prescribed drugs. Ser9Gly of the dopamine D3 receptor gene (P value .029) and 677-C/T of MTHFR (P value .029) were tested significant. Gly carriers and T-carriers, respectively, showed better clinical improvement on the positive scale. All other polymorphisms did not show any association with treatment response (all P values >.10). Conclusion: We were able to replicate only two of the previously reported associations between polymorphisms and treatment response. Heterogeneity in patient samples and outcome variables as well as publication bias and false positive findings may all play a role in lack of replication, found in our study, as in others. The direction of the associations presented here in D3 (Ser9Gly) and MTHFR (677-C/T) are in line with previous association studies in Caucasian patients. These polymorphisms may be of value for predicting clinical response.

Antipsychotic treatment response in caucasian patients

Background: The large variation in individual clinical responses to antipsychotic treatment hampers the management of psychotic disorders. Genetic factors are considered a main cause of this variation. Pharmacogenetics studies have demonstrated significant associations between several candidate genes (a.o. D2, D3, 5HTR2A and 5HTR2C, GRM3, COMT and MTHFR) and the response to antipsychotic drugs. The present study investigates the effect of 12 polymorphisms for an association with antipsychotic treatment response in patients with a psychotic disorder. Methods: 335 Caucasian patients with a non-affective psychotic disorder using antipsychotics were included. All patients participated in the longitudinal GROUP-study in The Netherlands. We genotyped 12 SNPs in 7 candidate genes (DRD2: TaqI-A, TaqI-D, -141-C, C957T; DRD3: Ser9Gly; HTR2A: 102-T/C, His452Tyr; HTR2C: Cys23Ser, -759-T/C; COMT: Val108/158Met; MTHFR: 677-C/T, GRM3: rs274622) using standard protocols. Polymorphisms were based on previous studies showing associations with treatment response. The Clinical Global Impression- Schizophrenia scale was cross-sectionally used to assess improvement in positive psychotic symptoms since the start of current antipsychotic treatment. Ordinal regression was used to test for an association between polymorphisms and improvement in positive symptoms. All polymorphisms were tested in an additive model, with minor allele dose as the dependent variable. Results: Ninety percent of the patients used atypical antipsychotics, with olanzapine (31%) and risperidone (29%) being the most prescribed drugs. Ser9Gly of the dopamine D3 receptor gene (P value .029) and 677-C/T of MTHFR (P value .029) were tested significant. Gly carriers and T-carriers, respectively, showed better clinical improvement on the positive scale. All other polymorphisms did not show any association with treatment response (all P values >.10). Conclusion: We were able to replicate only two of the previously reported associations between polymorphisms and treatment response. Heterogeneity in patient samples and outcome variables as well as publication bias and false positive findings may all play a role in lack of replication, found in our study, as in others. The direction of the associations presented here in D3 (Ser9Gly) and MTHFR (677-C/T) are in line with previous association studies in Caucasian patients. These polymorphisms may be of value for predicting clinical response.

Tardive dyskinesia and cytochrome P450 1A2 gene polymorphism in Russian patients with schizophrenia

Tardive dyskinesia (TD) is a potentially irreversible involuntary movement disorder with prevalence of about 20-30% in psychiatric patients on long-term treatment with antipsychotics. The identification of genetic factors contributing to development of TD would be of considerable clinical interest for individualized drug treatment. TD can be dissected into two distinct subsyndromes; orofaciolingual (TDof, involves movements of mouth and face) and limb-truncal dyskinesias (TDlt, involves purposeless choreiform movements of trunk and/or limbs) which probably have different genetic liability [1]. Recent investigations suggest that CYP1A2 may contribute to the development of TD as another CYP which may influence typical antipsychotics metabolism acting as a low-affinity high-capacity metabolizing enzyme [2,3]. Objective: The aim of this study was to investigate the association between orofaciolingual (TDof) and limb-truncal dyskinesias (TDlt) and Cyp1a2∗1F (C-163A, rs762551) polymorphism in Russian psychiatric inpatients. Methods: TD was assessed cross-sectionally in patients with clinically-established schizophrenia from four psychiatric centres in West Siberia by the use of the Abnormal Involuntary Movement Scale (AIMS). TDof and TDlt were assessed with AIMS items 1-4 and 5-7, respectively. Standard protocols were applied for genotyping. Analysis of covariance (ANCOVA) was used to compare the mean AIMS scores for each of the genotypic classes, with age, sex, duration of disease, chlorpromazine equivalent (CPZEQ) incorporated as covariates. Results: In total 319 Russian Caucasians patients (196 males, 123 females) with an age of 43±15.8 years (sample mean±SD) met the inclusion criteria. All patients had clinically-established schizophrenia and were included from four different psychiatric departments in West Siberia. Mean of disease duration was 17±14 years. The genotype distribution of Cyp1a2∗1F (C-163A, rs762551) polymorphism were in agreement with Hardy-Weinberg Equilibrium (Χ2 = 1.09, p=0.7). 44.8% were homozygous for the A-allele, 44.2% were heterozygous, and 10% were homozygous for the C-allele. Analysis of covariance (ANCOVA) with age, sex, duration of disease, chlorpromazine equivalent (CPZEQ) incorporated as covariates showed that TDlt, but not TDof, is an association with Cyp1a2∗1F (C-163A, rs762551) polymorphism (F = 3.27, p = 0.039). Patients with the C/C genotype had a higher mean AIMS items 5-7 score [2 (0-3.5)] [median (25%-75% percentiles)] than those with the A/C [1 (0-3)] or the A/A [0 (0-2)] genotype. Discussion: The increased TDlt severity in patients with the (C/C) genotype for CYP1A2 observed in the current study is in agreement with the literature data [2]. It should be noted that smoking is an estadlished inducer of CYP1A2 enzyme activity. Additionally, the plasma concentration of most typical antipsychotics is significantly reduced by smoking. It can be assumed that decrease of plasma level of typical antipsychotics in smokers are caused by activation of CYP1A2. 79% schizophrenic patients are smokers in our study and thus may have an increased CYP1A2-dependent pathway of metabolism of typical antipsychotics. Conclusions: C/C homozygounisity of rs762551might be associated with limb-trunkal but not with orofacial TD. Futher studies are needed to support our findings.