Patricia Gassó

Polymorphism of dopamine D2 receptor (TaqIA, TaqIB, and-141C Ins/Del) and dopamine degradation enzyme (COMT G158A, A-278G) genes and extrapyramidal symptoms in patients with schizophrenia and bipolar disorders

OBJECTIVE The relationship is examined of the dopamine D2 receptor (DRD2) polymorphism (TaqIA, TaqIB, -141 C Ins/Del) and the catechol-O-methyltransferase (COMT) polymorphism (A-278G, G158A) to the risk of antipsychotic-induced extrapyramidal symptoms (EPS) in schizophrenia and bipolar disorders. Participants comprised 80 cases presenting with EPS (Simpson-Angus Scale score >3) and 188 controls presenting without EPS (Simpson-Angus Scale score <or=3) participated in this study. The COMT(L) allele conferred a reduction of EPS risk of 60% to heterozygotes, but the finding did not survive correction for multiple comparisons. In the bipolar subgroup, with a COMT(L) allele protection of 70%, the reduction remained significant after Bonferroni correction. The analysis of the COMT haplotypes revealed an association of the A-G haplotype with EPS risk in the overall group and the bipolar disorder subgroup, and an association of the A-A haplotype with EPS protection in the bipolar subgroup. No significant associations were found for DRD2 or COMT A-278G polymorphisms. This is the first report of an association between the COMT polymorphism and EPS susceptibility. These results are of interest in view of the increased use of antipsychotic drugs in bipolar patients in both the acute manic and the depressive phase.

Dopamine transporter (DAT) genotype (VNTR) and phenotype in extrapyramidal symptoms induced by antipsychotics

INTRODUCTION Impaired dopamine transporter (DAT) function may be involved in antipsychotic (AP)-induced extrapyramidal symptoms (EPS). A polymorphism involving a variable number of tandem repeats (VNTR) has been described in the DAT gene (SLC6A3). OBJECTIVE We studied whether the SLC6A3 VNTR polymorphism is a risk or protection factor for AP-induced EPS. We also investigated the relationship between the polymorphism and DAT availability in the schizophrenic patients brain. METHODS Sixty-one patients receiving AP therapy participated in the EPS study. Of these, thirty-two cases presented EPS (Simpson-Angus >3) and twenty-nine without EPS (Simpson-Angus < or =3). The DAT expression was studied in fifteen AP-naive patients by [(123)I] FP-CIT SPECT. RESULTS No significant differences were observed for the more common alleles ((*)9R and (*)10R) or for genotype frequencies between patients with EPS and those without EPS. The frequency of the (*)9R and (*)10R alleles was similar to that described in other European populations. There were no significant differences in striatal DAT binding among the three major VNTR genotype groups. CONCLUSIONS Our results suggest that the VNTR polymorphism did not influence AP-induced EPS and did not affect DAT gene expression or protein function.

A common variant in DRD3 gene is associated with risperidone-induced extrapyramidal symptoms

We present a pharmacogenetic study of acute antipsychotic (AP)-induced extrapyramidal symptoms (EPS) using an extensive linkage disequilibrium mapping approach in seven-candidate genes with a well-established link to dopamine (DRD2, DRD3, ACE, COMT, DAT, MAO-A, MAO-B). From a cohort of 321 psychiatric inpatients, 81 cases presenting with EPS (Simpson–Angus >3) and 189 controls presenting without EPS (Simpson–Angus ⩽3) took part. Eighty-four-tag single nucleotide polymorphisms (SNPs) in candidate genes were genotyped. After extensive data cleaning, 70 SNPs were analyzed for association of single markers and haplotypes. AP dosage, AP-DRD2 blockade potency and age were identified as susceptibility factors for AP-induced EPS. One SNP of the DRD3 gene, rs167771, achieved significant association with EPS risk after Bonferroni correction (nominal P-value 1.3 × 10−4) in the patients treated with risperidone (132 patients). AP-induced EPS remains a serious public health problem. Our finding of a common SNP (rs167771) in the DRD3 gene provides a strong new candidate gene for risperidone-induced EPS.

CYP2D6*3, *4, *5 AND *6 POLYMORPHISMS AND ANTIPSYCHOTIC-INDUCED EXTRAPYRAMIDAL SIDE-EFFECTS IN PATIENTS RECEIVING ANTIPSYCHOTIC THERAPY

1 The aim of the present study was to examine the relationship between CYP2D6 polymorphisms and the risk of antipsychotic (AP)‐induced extrapyramidal symptoms (EPS) in patients receiving AP treatment. The allele status for CYP2D6*3, CYP2D6*4, CYP2D6*5 and CYP2D6*6 was determined in 267 patients receiving AP therapy. Seventy‐nine cases presenting with EPS (Simpson–Angus > 3) and 188 controls without EPS (Simpson‐Angus £ 3) took part in the study. 2 We found a non‐significant over‐representation of poor metaboliser genotypes among cases, but a significant association between the mutant homozygous genotype for CYP2D6*4 (odds ratio (OR) 4.1, 95% confidence interval (CI) 1.01–16, permutated P value 0.01) and the heterozygous genotype for CYP2D6*6 (OR 5.4, 95% CI 1.13–18, permutated P value 0.003) and the risk of suffering EPS. 3 These results suggest that the CYP2D6 genotype may be a contributory factor in the development of EPS in patients undergoing AP therapy.

Insertion/deletion polymorphism of the angiotensin-converting enzyme gene is associated with schizophrenia in a Spanish population

A number of factors make the angiotensin-converting enzyme (ACE) a candidate gene for psychiatric disorders, including its action on neurotransmitters such as dopamine. An insertion/deletion (I/D) polymorphism in an ACE gene intron is associated with ACE levels. Here we examine whether the ACE I/D polymorphism is a risk factor for schizophrenia. Participants comprised 243 subjects diagnosed with schizophrenia and related disorders, and 291 hospital-based controls. The D allele of the ACE gene was identified as a protective factor, significantly reducing the risk of developing schizophrenia and related disorders (by 40%) and of developing schizophrenia (by 50%). This protection is explained by the additive genotype risk model, in which the protection increases with the number of D alleles. Our results indicate that the ACE D allele is involved in the development of schizophrenia.

Neurotoxic/neuroprotective activity of haloperidol, risperidone and paliperidone in neuroblastoma cells.

The neurotoxicity of antipsychotic (AP) drugs seems to be linked with neurological side effects like extrapyramidal symptoms (EPS). On the other hand, neuroprotective effects can mitigate or slow the progressive degenerative structural changes in the brain leading to improved outcome of schizophrenia. First and second-generation antipsychotics may differ in their neurotoxic and neuroprotective properties. The aim of this study was to compare the neurotoxic/neuroprotective activity of haloperidol, a first-generation antipsychotic, and risperidone, a second-generation one, with paliperidone, a relatively new second-generation antipsychotic, in SK-N-SH cells. Haloperidol, risperidone and paliperidone (10, 50, 100 μM) were administered, either alone or in combination with dopamine (100 μM), to human neuroblastoma SK-N-SH. We examined the effects of the drugs on cell viability (measured by alamarBlue®), caspase-3 activity (measured by fluorimetric assay) and cell death (by measuring the externalization of phosphatidylserine). Haloperidol significantly decreased cell viability and increased caspase-3 activity and cell death. Risperidone and paliperidone did not affect cell viability or cell death. Both second-generation APs decreased caspase-3 activity, especially paliperidone. In cells treated with dopamine in combination with antipsychotics, only paliperidone (10 μM) induced a slight improvement in cell viability. While haloperidol potentiated the dopamine-induced increase in caspase-3 activity, risperidone and paliperidone reduced this effect. The results indicate that haloperidol induces apoptosis, whereas risperidone and paliperidone may afford protection against it. Of the APs tested, paliperidone always showed the strongest neuroprotective effect. The different antipsychotic effects on survival and cell death might be related to differences in their capacity to induce EPS.

Pharmacogenetic predictors of angiotensin-converting enzyme inhibitor-induced cough: the role of ace , abo , and bdkrb2 genes

Background and objective Dry cough is the most common reason for stopping angiotensin-converting enzyme inhibitors (ACEi) therapy. The role of ACE in the metabolism of bradykinin has been proposed as a pathogenic mechanism. This study included a complete analysis of the variability of the genes involved in bradykinin metabolism (ACE and XPNPEP2) and bradykinin receptors (BDKRB2). We included two polymorphisms in the ABO (related to ACE levels); two polymorphisms in the AGTR1, and one polymorphism in the BKRB1 (related to ACEi response). Methods A total of 281 patients who had been treated with ACEi were retrospectively recruited [102 patients were considered as cases (cough) and 179 patients were considered as controls (no cough)], and 56 polymorphisms were tested for association. Results We found that genetic polymorphisms in BDKRB2 [rs8016905; P=0.003; odds ratio (OR)=2.21] and ABO (rs495828; P=0.001; OR=2.45) are associated with ACEi-induced cough after correction for multiple testing. The effect of polymorphisms in ABO was sex specific (female patients; P=0.0006; OR=3.26). When we analyzed the subgroup of patients homozygous GG for rs4343, two polymorphisms in the ACE were found to have protective properties (rs4459610 and rs4267385; P=0.005 and 0.004; OR=0.25). We also found a strong interaction between the ABO polymorphisms, rs495828 and rs8176746 (P<0.0001; OR=3.7). Conclusion These results highlight the importance of genetic determinants of ACE levels as good predictors of the ACEi response, and provide ABO as a good candidate gene for pharmacogenetic studies of ACEi-related cough. Moreover, our results also confirm the importance of bradykinin in the pathogenesis of this adverse effect.

Increased susceptibility to apoptosis in cultured fibroblasts from antipsychotic-naïve first-episode schizophrenia patients

Altered apoptosis has been proposed as a potential mechanism involved in the abnormal neurodevelopment and neurodegenerative processes associated with schizophrenia. The aim of this study was to investigate in primary fibroblast cultures whether antipsychotic-naïve patients with first-episode schizophrenia have greater apoptotic susceptibility than healthy controls. Cell growth, cell viability and various apoptotic hallmarks (caspase-3 activity, translocation of phosphatidylserine, chromatin condensation and gene expression of AKT1, BAX, BCL2, CASP3, GSK3B and P53) were measured in fibroblast cultures obtained from skin biopsies of patients (n = 11) and healthy controls (n = 8), both in basal conditions and after inducing apoptosis with staurosporine. Compared to controls, cultured fibroblasts from patients showed higher caspase-3 activity and lower BCL2 expression. When exposed to staurosporine, fibroblasts from patients also showed higher caspase-3 activity; a higher percentage of cells with translocated phosphatidylserine and condensed chromatin; and higher p53 expression compared to fibroblasts from controls. No differences in cell viability or cell growth were detected. These results strongly support the hypothesis that first-episode schizophrenia patients may have increased susceptibility to apoptosis, which may be involved in the onset and progression of the disease.

SIMULTANEOUS GENOTYPING OF CYP2D6*3, *4, *5 AND *6 POLYMORPHISMS IN A SPANISH POPULATION THROUGH MULTIPLEX LONG POLYMERASE CHAIN REACTION AND MINISEQUENCING MULTIPLEX SINGLE BASE EXTENSION ANALYSIS

1 The aim of the present study was to perform a descriptive study of the prevalence of the four major CYP2D6 poor metaboliser (PM) alleles (*3, *4, *5 and *6) in a Spanish population (n = 290) using a method based on a new combination of multiplex long polymerase chain reaction (PCR) and minisequencing through multiplex single base extension (SBE) analysis. 2 The method was validated using different strategies, such as allelic discrimination assay and PCR–restriction fragment length polymorphism (RFLP). 3 The allele frequencies were similar to those described for other Spanish populations, namely 0.9% (95% confidence interval (CI) 0.5–1.3), 16.4% (95% CI 14.9–18.0), 2.7% (95% CI 2.0–3.4) and 0.7% (95% CI 0.3–1.0) for the *3, *4, *5 and *6 alleles, respectively. The results were satisfactory and left little doubt as to the genotypes, which were confirmed either by allelic discrimination assay (*4 and *6) or PCR‐RFLP (*3) with 100% concordance. 4 The present study corroborates the low prevalence of the most frequent polymorphism (CYP2D6*4) that leads to null CYP2D6 activity in Spain and the allelic geographical gradient between Caucasian populations in the north and south. The present study reports a technique for the detection of four polymorphisms that account for 98% of the CYP2D6 defect alleles. This multiplex long PCR–SBE technique is a combination of several known methods to genotype CYP2D6 alleles (*3, *4, *5 and*6). Given the importance of CYP2D6 in drug metabolism and the need to genotype a large number of samples, we believe that this method will find broad application.

-141C Ins/Del polymorphism of the dopamine D2 receptor gene is associated with schizophrenia in a Spanish population.

Objective In this study we examined the relationship between dopamine D2 receptor (DRD2) polymorphisms (TaqIA, TaqIB, -141C Ins/Del) and dopamine D3 receptor (DRD3) Ser9Gly polymorphism and the risk of schizophrenia in a Spanish population. Methods Two hundred and forty-three schizophrenia patients and 291 healthy controls from the general population participated in a case–control study. Results No significant differences were observed in the allele or genotype frequencies of TaqIA, TaqIB or Ser9Gly polymorphisms between the schizophrenia patients and the healthy controls. The frequency of the -141C Del allele was significantly lower in the former group (odds ratio=0.4, P=0.01). The -141C Del allele, which produces lower expression of DRD2, may protect against dopaminergic hyperactivity in schizophrenia. Conclusion This study is one of the few studies of Caucasian participants that supports the results obtained in the original Japanese study, in which the -141C Ins/Del polymorphism was first described. Furthermore, our findings reinforce the hypothesis that excess dopaminergic activity leads to schizophrenia.