Major depressive disorder (MDD) is a severe psychiatric disorder with a lifetime prevalence of about 15%.1 The importance of the genetic component is well accepted,2 but the mode of inheritance is ...complex and non-Mendelian. A line of evidence suggests the involvement of serotonin and dopamine neurotransmitters in the pathophysiology of depression. In the present study, 102 unipolar MDD patients and 172 healthy controls were genotyped for polymorphisms in four serotonergic and three dopaminergic candidate genes tryptophan hydroxylase (TPH), serotonin receptor 2A (HTR2A), serotonin receptor 2C (HTR2C), serotonin transporter promoter region (5-HTTLPR), dopamine receptor D4 (DRD4), dopamine transporter (DAT1) and catechol-O-methyl transferase (COMT). There were no statistical differences between MDD patients and healthy controls in the genotypic and allelic distribution of all polymorphisms investigated. Thus, our study does not support a major role for these polymorphisms in contributing to susceptibility to MDD, although it does not preclude minor effects.
Obsessive-compulsive disorder (OCD) is a severe and disabling anxiety disorder with a marked genetic contribution. Pharmacological data indicated involvement of the serotonergic and dopaminergic ...systems. We studied the association between OCD and six candidate genes encoding important components of the serotonergic and dopaminergic pathways in 75 biologically unrelated patients and 172 ethnically matched controls (Ashkenazi and non-Ashkenazi Jews). Polymorphisms in the following genes were studied: tryptophan hydroxylase (TPH), serotonin 2A receptor (HTR2A), serotonin 2C receptor (HTR2C), serotonin transporter (5-HTT), dopamine receptor D4 (DRD4), and dopamine transporter (DAT1). The genotypic and allelic distribution of all polymorphisms tested did not show statistically significant differences between patients and controls. Our results suggest that these polymorphisms do not play a major role in the genetic predisposition to OCD, although a minor contribution cannot be ruled out.
Serotonergic neurotransmission has been implicated in suicidal behavior. Polymorphisms in the genes coding for tryptophan hydroxylase, serotonin receptor 2A and serotonin transporter were ...investigated in a sample of suicide attempters (n = 165) and healthy control subjects (n = 99). No significant differences were found for any of the investigated polymorphisms. Neither did any significant differences emerge in comparison with control subjects when the suicide attempters were grouped into different diagnostic categories: unipolar disorder (n = 45), adjustment disorder (n = 37), substance use disorder (n = 37) and personality disorder, cluster B (n = 36). The results suggest that alleles defined by the investigated polymorphisms do not represent a major determinant in suicide attempt. However, a highly significant (P = 0.001; odds ratio, 1.47; 99% confidence interval, 1.42-1.53) allelic association between tryptophan hydroxylase and suicide attempt is indicated after pooling our data with literature data. In light of previous data, a possible association between the tryptophan hydroxylase polymorphism and a phenotype that may become differently stratified within differently selected samples of suicide attempters is discussed.
The human serotonin transporter (hSERT) gene is a promising candidate for mediating the genetic susceptibility for various psychiatric conditions such as mood and obsessive-compulsive disorders. Two ...polymorphic sites in this gene attracted much interest: a VNTR of 17-bp repeats in intron two, and an insertion/deletion in the 5'-flanking promoter region (5-HTT gene-linked polymorphic region-5-HTTLPR) creating a short (S) and a long (L) allele. The 5-HTTLPR polymorphism is situated in a GC-rich region composed of 20-23 bp repeating units. The S and L alleles have 14 and 16 repeat-elements respectively. Positive associations of the 5-HTTLPR polymorphism with mood disorders, anxiety-related personality traits, autism and late-onset Alzheimer's disease have been published, although some non replications were also reported. Here we report a novel allele (termed LJ) in the 5-HTTLPR site. This allele is longer than the L allele by 43 bp, has 18 repeat units and contains two copies of the insertion/deletion sequence arranged in tandem. The LJ allele was found in individuals of Libyan and Tunisian Jewish origin but not in Moroccan or Ashkenazi Jews.
An association between long alleles of a variable number tandem repeat (VNTR) polymorphism in the dopamine receptor D4 gene and the extraversion related personality traits Excitement and Novelty ...Seeking has been reported in healthy subjects. In an attempt to replicate the previous findings, 256 healthy Caucasian volunteers were analysed for a potential relationship between the dopamine receptor D4 exon III VNTR polymorphism and Extraversion as assessed by the Revised Neo Personality Inventory (NEO PI-R). The present study did not yield evidence for an association between Extraversion and the dopamine receptor D4 polymorphism.
Dopaminergic neurotransmission has been implicated in suicidal behaviour. The 48 bp-repeat polymorphism in the gene coding for dopamine receptor D4 was investigated in a sample of suicide attempters ...(n = 165) and healthy control subjects (n = 99). No association between suicide attempts and this polymorphism was observed. Neither did any significant differences emerge in comparison with control subjects when the suicide attempters were grouped into different diagnostic categories: unipolar (n = 45), anxiety (n = 23), adjustment (n = 37) and personality disorders, cluster B (n = 36). The results suggest that alleles defined by the investigated polymorphism do not have a major impact on suicidal behaviour.
Velo-cardio-facial syndrome (VCFS) is caused by a microdeletion in the long arm of chromosome 22 and is associated with an increased frequency of schizophrenia and bipolar mood disorder. The purpose ...of this study was to investigate the genetic, physical, developmental and psychiatric features of schizophrenic patients with VCFS microdeletion. It describes the clinical findings in four schizophrenic inpatients with the characteristic chromosomal deletion. The four patients displayed delayed motor development, language deficits, learning disabilities, mental retardation, early age of onset, chronic and disabling course of illness and poor response to classical neuroleptic drugs and electroconvulsive therapy. Two patients benefited from treatment with clozapine. We suggest that schizophrenic patients with a history of delayed motor development, early onset of the disorder, history of learning disability, mental retardation, congenital cardiac anomalies and/or hypernasal speech should be screened for the velo-cardio-facial syndrome deletion. The implications of this study for psychiatric phenotype, nosology, disease mechanism, and possible new treatments in the future are discussed.
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