Pharmacogenetics of tardive dyskinesia in schizophrenia: The role of CHRM1 and CHRM2 muscarinic receptors

Objectives: Acetylcholine M (muscarinic) receptors are possibly involved in tardive dyskinesia (TD). The authors tried to verify this hypothesis by testing for possible associations between two muscarinic receptor genes (CHRM1 and CHRM2) polymorphisms and TD in patients with schizophrenia.Methods: A total of 472 patients with schizophrenia were recruited. TD was assessed cross-sectionally using the Abnormal Involuntary Movement Scale. Fourteen allelic variants of CHRM1 and CHRM2 were genotyped using Applied Biosystems amplifiers (USA) and the MassARRAY System by Agena Bioscience.Results: The prevalence of the rs1824024*GG genotype of the CHRM2 gene was lower in TD patients compared to the group without it (χ2 = 6.035, p = 0.049). This suggested that this genotype has a protective effect for the development of TD (OR = 0.4, 95% CI: 0.19-0.88). When age, gender, duration of schizophrenia and dosage of antipsychotic treatment were added as covariates in regression analysis, the results did not reach statistical significance.Conclusions: This study did identify associations between CHRM2 variations and TD; the results of logistic regression analysis with covariates suggest that the association is, however, likely to be secondary to other concomitant factors.

Dried Blood Spot Analysis for Therapeutic Drug Monitoring of Clozapine

BACKGROUND

Schizophrenia is a psychiatric disorder that affects approximately 0.4%-1% of the population worldwide. Diagnosis of schizophrenia is based primarily on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria. Clozapine is an antipsychotic drug that is mainly used in the treatment of schizophrenia patients who are refractory or intolerant to at least 2 other antipsychotics. Due to the high variability in pharmacokinetics of clozapine, therapeutic drug monitoring (TDM) is highly recommended for clozapine therapy.

OBJECTIVE

To develop and clinically validate a novel sampling method using dried blood spot (DBS) to support TDM of clozapine and norclozapine.

METHODS

From June 2014 to September 2014, 15 schizophrenia patients (18-55 years) treated with clozapine were included. Plasma, DBS samples made from venous samples (VDBS), and finger prick DBS (DBS) samples were obtained before administration and 2, 4, 6, and 8 hours after clozapine intake. The study was repeated in 6 Russian patients for external validation. Passing-Bablok regression and Bland-Altman analysis were used to compare the DBS, VDBS, and plasma results for clozapine and norclozapine.

RESULTS

The DBS validation results showed good linearity over the concentration time curve measured for clozapine and norclozapine. The accuracy and between- and within-day precision variation values were within accepted ranges. Different blood spot volumes and hematocrit values had no significant influence on the results. The DBS samples were stable at 20°C and 37°C for 2 weeks and at -20°C for 2 years. The mean clozapine and norclozapine DBS/plasma ratios were, respectively, 0.80 (95% CI, 0.76 to 0.85) and 1.063 (95% CI, 1.027 to 1.099) in Dutch patients. The mean clozapine DBS/DPS ratio in Russian patients was 0.70 (95% CI, 0.64 to 0.76).

CONCLUSION

DBS analysis is a reliable tool for blood sampling and performing TDM of clozapine and norclozapine in daily practice and substantially extends the opportunities for TDM of clozapine.

[Antibodies to native and denatured DNA in the serum of patients with schizophrenia depending on the clinical features of the disease]

OBJECTIVE

To study the correlations between the level of antibodies to native and denatured DNA and psychopathological symptoms and illness duration in patients with schizophrenia.

MATERIAL AND METHODS

The level of antibodies to native (double-stranded) DNA and denatured (single-stranded) DNA was studied in the serum of 50 patients with schizophrenia, including 12 patients with tardive dyskinesia (TD). The control group consisted of 30 people.

RESULTS

A significant twofold increase in antibodies to native DNA was detected in patients with TD. There was no correlation of the amount of antibodies to double-stranded DNA with the duration of disease and leading symptoms both between the groups of patients as well as in comparison with controls. A significant decrease in antibody levels to the denatured (single-stranded) DNA was found in schizophrenic patients compared to the control group (p=0.009). A significant decrease in the concentration of antibodies to single-stranded DNA in patients with increasing duration of the disease, as well as in patients with leading negative symptoms was revealed.

CONCLUSION

The results suggest that anti-DNAantibodies may not play a major role in the pathogenesis of schizophrenia.

[Association study of genetic markers of schizophrenia and its cognitive endophenotypes]

A replicative analysis of associations of 15 SNPs located in the regions of 11 genes (TCF4, VRK2, NOTCH4, ZNF804A, AGBL1, RELN, ZFP64P1, KCNB2, CSMD1, CPVL, NRIP1) and three intergenic regions (SLCO6A1/LINCOO491, LOC105376248/LOC105376249, SPA17/NRGN) with schizophrenia was conducted in the Russian population of the Siberian region. These SNPs were previously identified in genome-wide association studies (GWAS) of schizophrenia and cognitive abnormalities. The present study confirmed associations of KCNB2 rs2247572, CSMD1 rs2616984, and intergenic rs12807809 located in SPA17/NRGN with schizophrenia. It was established that the frequency of the CSMD1 rs2616984 G/G genotype was higher in patients compared to the control group (OR = 1.73; CI: 1.14–2.62; р = 0.0337). The frequencies of the KCNB2 rs2247572 TT genotype (OR = 0.41; CI: 0.20–0.87; р = 0.0485) and intergenic rs12807809 CT genotype located in SPA17/NRGN (OR = 0.70; CI: 0.53–0.94; р = 0.0464) were significantly decreased in patients compared to the control group.

[An effect of quetiapine on the immune system of patients with schizophrenia]

AIM

To study an effect of the atypical antipsychotic quetiapine on the immune system of patients with schizophrenia with account for treatment efficacy.

MATERIAL AND METHODS

Quetiapine was administered to 27 patients diagnosed with residual schizophrenia (F20.5) for 6 weeks in dose 200-400 mg/day; dynamic of clinical symptoms was evaluated with PANSS и CGI scales before administration of quetiapine and by week 6 of the treatment. Along with clinical assessments, immune indices were determined.

RESULTS

At the end of week 6 of treatment, statistically significant changes of PANSS psychopathological symptoms were noted. According to CGI scale, patients were divided into group 1 with high treatment efficacy (n=17) and group 2 with the low efficacy (n=10). Significant between-group differences before treatment were as follows: the decreased number of lymphocytes of CD3+- CD16+-phenotypes, increased number of HLADR+-lymphocytes and IgA level in group 2. The quetiapine therapy led to the positive dynamic of phagocytosis indices, CD16+-lymphocytes, decrease in the level of IgA.

CONCLUSION

Possible predictors of treatment efficacy were found including the number of mature T (CD3+) lymphocytes, CD16+ natural killers, HLADR+ lymphocytes and IgA concentrations.

[Association of (N251S)-PIP5K2A with schizophrenic disorders: a study of the Russian population of Siberia]

The phosphatidylinositol-4-phosphate-5-kinase type IIa (PIP5K2A) gene has been proposed as a putative susceptibility gene for schizophrenia on both positional and functional grounds. The association between the (N251S)-PIP5K2A (rs10828317) variant and schizophrenia was found in German and Dutch populations but was not replicated in several other populations. The purpose of the study was to examine whether the previously implicated (N251S)-PIP5K2A variant influences susceptibility to schizophrenia in the Russian population of Siberia. Authors studied 355 patients with schizophrenic disorders from the Russian population of Siberia. The control group consisted of 100 healthy. Results confirm the association of the (N251S)-PIP5K2A (rs10828317) polymorphism with schizophrenia (p=0.04, OR=2.48, 95%CI=1.19--5.17 for the CC genotype). The association can be explained by the inability of mutant kinase to activate the phosphatidylinositol-4,5-biphosphate dependent proteins, including neuronal KCNQ channels and glutamate EAAT3 transporters, which leads to the lack of dopaminergic and glutamatergic control in schizophrenic patients carriers of this mutation.

NMDA receptor genotypes associated with the vulnerability to develop dyskinesia

Dyskinesias are involuntary muscle movements that occur spontaneously in Huntington's disease (HD) and after long-term treatments for Parkinson's 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.

[Clinical and experimental research of immunomodulatory effect of amisulpride]

Study of immunomodulatory effect of atypical antipsychotic amisulpride has revealed a positive clinical effect after 6-week therapy of schizophrenic patients regarding both positive and negative symptoms. A decrease in activity of humoral immunity factors (B lymphocytes, immunoglobulins, HLADR(+)-cells) identified among schizophrenic patients in the process of amisulpride therapy can be attributed to a positive effect optimizing the ratio Th1/Th2. Amisulpride when used under experimental conditions produced a suppression of IgM-immune response in mice of the C57BL/6J strain. This effect was more expressed in animals with aggressive behavior pattern.