Sami Anttila

Interaction between 5-HT1A and BDNF genotypes increases the risk of treatment-resistant depression.

SummarySeveral studies have linked 5-HT1A C1019G and BDNF G196A (Val66Met) gene polymorphisms to major depressive disorder (MDD) and the actions of antidepressants. We attempt to show that the interaction between 5-HT1A and BDNF polymorphism predicts the risk of treatment-resistant depression. The sample consists of 119 patients with treatment-resistant MDD and 392 controls. 5-HT1A C1019G and BDNF G196A (Val66Met) polymorphisms were studied. The combination of 5-HT1A GG and BDNF GA + AA genotypes is associated with an increased risk of depression.

Vascular endothelial growth factor (VEGF) polymorphism is associated with treatment resistant depression

Antidepressive medication and electroconvulsive therapy (ECT) increase hippocampal neurogenesis by promoting expression of trophic factors, including brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF). The aims were to test for an association between the VEGF 2578 C/A polymorphism and major depressive disorder (MDD) in two patient populations compared to controls, and the association between this polymorphism and response to serotonin selective reuptake inhibitors (SSRI) and to ECT. The first patient sample consisted of 119 subjects with treatment resistant major depressive disorder who were treated with ECT and the second of 98 depressive patients treated with SSRI. Treatment response was assessed by the Montgomery and Asberg Depression Rating Scale (MADRS). Patients scoring <8 in post-treatment MADRS were considered remitters. There was a trend that CC genotype of VEGF 2578C/A polymorphism was more common in ECT-treated and SSRI-treated patients than in controls (31.1%, 25.5% and 18.7% respectively; p=0.056). The VEGF 2578 C/A polymorphism was associated with treatment resistant MDD. CC genotype was more common in ECT patients than in controls (31.1% and 18.7% respectively; p=0.015). The VEGF 2578 C/A polymorphism was not associated with treatment response to SSRI or to ECT. The finding suggests an association between VEGF 2578 C/A polymorphism and treatment resistant depression which is reported for the first time. Further studies with larger samples will be required to confirm the results.

Neuregulin genotype and medication response in Finnish patients with schizophrenia.

Neuregulin 1 is involved both in neurodevelopment and neurotransmitter mechanisms in the brain. There is evidence of an association between neuregulin 1 genotype and schizophrenia. We compared neuregulin 1 genotypes in patients with schizophrenia (n=94) and control subjects (n=395) of Finnish origin by using one SNP (SNP8NRG221533) as a genetic marker. We also analyzed NRG1 genotype with regard to age at onset and between responders and non-responders to conventional antipsychotics. The NRG1 genotype or allele frequencies showed similar distributions between patient and control groups. Age at onset was not associated with NRG1 genotype. The TT genotype was overrepresented in the non-responders group compared with the responders (p=0.013). Further studies are needed to ascertain the significance of neuregulin genotype in medication response to schizophrenia.

Lack of association between two polymorphisms of brain-derived neurotrophic factor and response to typical neuroleptics

Summary.Several studies have connected brain-derived neurotrophic factor (BDNF) with treatment response to neuroleptics. In recent studies, the BDNF expression was reduced by typical neuroleptics. We conducted a retrospective study on 94 patients with schizophrenia and 98 controls. The BDNF G196A and C270T polymorphisms are not associated with treatment response to typical neuroleptics or with age at first hospitalization. Moreover, these polymorphisms of the BDNF gene are not associated with the risk of schizophrenia.

Catechol-O-methyltransferase and monoamine oxidase A genotypes and drug response to conventional neuroleptics in schizophrenia.

Biogenic amine synthesis and degradation are involved in the pathogenesis of schizophrenia. Catechol-O-methyltransferase and monoamine oxidase enzymes are important agents in the metabolic inactivation of these neurotransmitters (ie, dopamine, serotonin, and norepinephrine). Functional polymorphism in the catechol-O-methyltransferase and monoamine oxidase A genes causes variation in enzyme activities. We investigated the relationship of catechol-O-methyltransferase Val158Met and monoamine oxidase A promoter repeat polymorphism with response to conventional neuroleptic treatment in schizophrenia. Ninety-four schizophrenic patients formed 2 different study populations. The responders had experienced a fair and steady response to conventional neuroleptics. The nonresponders had failed to achieve an acceptable response to conventional neuroleptics. We also used a control population of 94 age-matched and gender-matched blood donors. Genotyping of the catechol-O-methyltransferase and monoamine oxidase A genes was performed by polymerase chain reaction. Forty-three percent of the nonresponders had a low activity catechol-O-methyltransferase genotype compared with 16% of the responders (P = 0.009). Monoamine oxidase A genotype alone did not differ significantly between the groups. Moreover, the risk of having both low-activity catechol-O-methyltransferase and monoamine oxidase A genotypes was over 6 times more common (odds ratio = 6.16, P = 0.03) in the nonresponders compared with responders. The whole population of patients with schizophrenia did not differ from the controls. The low-activity catechol-O-methyltransferase genotype may be associated with unsatisfactory drug response to conventional neuroleptics or alternatively be involved in a subset of schizophrenics. The role of monoamine oxidase A genotype seems to be additive in this respect.

Interaction between NOTCH4 and catechol-O-methyltransferase genotypes in schizophrenia patients with poor response to typical neuroleptics.

OBJECTIVE In this study we attempted to show that the interaction between NOTCH4 and catechol-O-methyltransferase (COMT) polymorphism predicts the response to typical neuroleptics in schizophrenia. Our sample consisted of 94 Finnish patients with DSM-IV schizophrenia and 98 controls. METHODS Several studies have connected COMT and NOTCH4 genes to schizophrenia. We have previously shown that COMT polymorphism is significantly associated with treatment response in schizophrenia. NOTCH4 SNP2 polymorphism has been associated with age of onset in schizophrenia, but there is also a trend that this polymorphism may predict response to typical neuroleptics. In the present sample, there is a strong gene-gene interaction between these genes (P = 0.003) and they have additive effect in treatment response. RESULTS Patients carrying both NOTCH4 C/C genotype and COMT low/low genotype, had more than ten times higher risk of being a non-responder than responder to treatment with typical neuroleptics [OR = 10.25 (95% CI 2.21-47.53), P < 0.001]. This combination of genotypes is also more common in patients considered non-responders than in controls [OR = 3.00 (95% CI 1.33-6.76), P = 0.007]. CONCLUSION Our results suggest that an interaction between COMT and NOTCH4 genotypes may predict the treatment response to typical neuroleptics in patients with schizophrenia.

TPH1 218A/C polymorphism is associated with major depressive disorder and its treatment response

The association between the tryptophan hydroxylase 1 (TPH1) 218A/C polymorphism and (1) severity of major depressive disorder (MDD) and (2) response to treatment was studied. There were three study populations, the first consisting of 119 treatment-resistant MDD inpatients treated with electro-convulsive therapy (ECT), and the second of 98 MDD open care patients treated with selective serotonin reuptake inhibitors (SSRI). In addition, there was a control population of 395 healthy blood donors. The first aim of the study was to compare the genotypes of the patient with those of the healthy controls and between patient populations. The second aim was to compare the genotypes of MDD patients achieving remission with basic SSRI treatment (MADRS<8) with the genotypes of non-responders to ECT (defined as MADRS>15). TPH1 218A/C polymorphism was associated with the risk of MDD. CC genotype was significantly more common in patients (including both ECT and SSRI treated patients) than in controls (38.2% and 26.8% respectively; p=0.008), and its frequency was significantly higher in more severe forms of depression, i.e. in ECT treated patients compared with SSRI treated patients (42.0% and 33.7%, p=0.026). CC genotype was also associated with lower probability of achieving remission. It was significantly more frequent among ECT non-responders than among SSRI remitters (53.1% and 23.3%, p=0.049). In this Finnish population TPH1 218A/C polymorphism was associated with the risk of MDD and treatment response; CC genotype was associated with the increased risk of MDD and lower probability of responding treatment. Further studies with larger samples will be required to confirm the results.

Dopamine 2 receptor C957T and catechol-o-methyltransferase Val158Met polymorphisms are associated with treatment response in electroconvulsive therapy

Alterations in dopamine levels and dopamine receptors in brain are suggested to be associated with treatment response in electroconvulsive therapy (ECT). Dopamine 2 receptor gene (DRD2) polymorphism C957T (rs6277) and cathechol-o-methyltransferase (COMT) polymorphism Val158Met (rs4680) interaction was studied in 118 patients suffering from major depressive disorder (MDD) treated with ECT and 383 healthy controls. It was found that the combination of COMT Met allele and DRD2 T allele predicted more severe depression in those already affected but did not predict the risk of depression when compared to normal population. The genotype modified the response to ECT. The patients with TT genotype of D2 receptor gene C957T polymorphism combined with COMT gene polymorphism Met/Met genotype did not achieve remission as often as those with CC genotype of DRD2 C957T combined with COMT Val/Val genotype. Thus the interaction of these polymorphisms may be associated with response to ECT.

Interaction between angiotensin-converting enzyme and catechol-O-methyltransferase genotypes in schizophrenics with poor response to conventional neuroleptics

Angiotensin-converting enzyme (ACE) modulates dopamine turnover in the brain and catechol-O-methyltransferase (COMT) enzyme is an important agent in the metabolic inactivation of dopamine and norepinephrine. Functional polymorphism in the COMT and ACE genes causes variation in enzyme activities. We investigated the relationship of COMT and ACE gene polymorphism with response to conventional neuroleptic treatment in schizophrenia. In this study population we had earlier detected that COMT genotype is associated with unsatisfactory drug response. A total of 94 schizophrenic patients were evaluated either as responders (n=43) or non-responders (n=51). The responders had experienced a fair and steady response to conventional neuroleptics. The non-responders had failed to achieve an acceptable response to conventional neuroleptics. We also used a control population of 94 age- and gender-matched blood donors. Genotyping of the COMT and ACE genes was performed by polymerase chain reaction. The risk of having both low activity COMT and high activity ACE genotypes was over 10 times higher (odds ratio=10.89, 95%CI 1.14-103.98, P=0.04) in the non-responders compared to responders. ACE genotype alone did not differ between any groups. This finding may suggest a possible interaction with low activity COMT and high activity ACE genotype in association with poor response to conventional neuroleptics.

Association of EGF polymorphism with schizophrenia in Finnish men

Some recent data suggest that epidermal growth factor (EGF) protein levels are altered in the brain of schizophrenic patients. In addition, a novel polymorphism of the EGF gene is associated with enhanced production of EGF in vitro. We conducted a retrospective study to explore the impact of EGF polymorphism on factors associated with schizophrenia. The sample consisted of 94 patients with schizophrenia who had either responded to treatment with conventional neuroleptics or who were considered non-responders. The control sample consisted of 98 blood donors. In our sample, the G allele was associated with schizophrenia in male patients (OR = 3.594 (95% CI 1.347–9.591), p = 0.008). The G allele was also associated with a later age at onset in male patients with schizophrenia. However, no association was found between treatment response and EGF polymorphism.