Polymorphism in the serotonin transporter gene and response to treatment in African American cocaine and alcohol-abusing individuals.

The serotonin transporter (5-HTT) regulates serotonin transmission and modulates behavioral effects of drug of abuse. A polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) yielding a short (S) and long (L) allele has been associated with severity of substance abuse. The aims of the study were to investigate whether 5-HTTLPR genotypes differed in their response to treatment in cocaine- and alcohol-abusing patients. Polymerase chain reaction-based genotyping of a 44 base pair insertion/deletion polymorphism was performed in 141 African American cocaine-dependent patients with concurrent alcohol use who were entering a 12-week behaviorally oriented outpatient treatment program. In treatment, end of treatment and 6-month follow-up outcome measures included changes in Addiction Severity Index (ASI) scores, urine drug screens, days in treatment, individual/group sessions, dropout and completion rates. As expected, there was a reduction in substance abuse by the end of treatment and follow-up (F = 5.15, p = 0.000). However, there were no differences in the reduction in cocaine use across the LL, LS and SS genotypes. Interestingly, individuals with the S allele showed greater severity of alcohol use at admission (F = 4.84, p = 0.03), and the SS genotype showed less improvement in alcohol measures than the LL at follow-up (F = 3.68, p = 0.03), after controlling for baseline variables. While we found no association of the 5-HTTLPR variants with severity of cocaine abuse or any cocaine-related outcome measures, the data suggested that the 5-HTTLPR polymorphism may distinguish responders from non-responders to behavioral treatment in terms of alcohol use. Further investigations are required to determine the role of the 5-HTTLPR polymorphism in influencing treatment - outcome among substance abusers.

Transcription factor AP-2beta genotype associated with anxiety-related personality traits in women. A replication study.

Attempts to link transmitter system genes to certain aspects of personality have been performed. Several monoamine-related gene variants have been investigated. We previously reported an association between a transcription factor activating protein-2beta (AP-2beta) variant and anxiety-related personality traits as estimated by Karolinska Scales of Personality (KSP). To confirm this reported association, we have, in the present study, analysed an enlarged group of healthy volunteers (n = 370) with regard to AP-2beta genotype and personality traits. For estimation of personality traits, individuals completed 5 different personality questionnaires, i.e. Swedish Universities Scales of Personality (SSP), Health-Relevant 5- Factor Personality Inventory (HP5i), Temperament and Character Inventory, the Revised NEO Personality Inventory and KSP. In contrast to men, women having two long AP-2beta alleles displayed lower scores for muscular tension (KSP; F = 10.65, p = 0.0013), somatic trait anxiety (SSP; F = 7.18, p = 0.0081), trait irritability (SSP; F = 4.51, p = 0.032), mistrust (SSP; F = 4.01, p = 0.0468) and negative affectivity (HP5i; F = 10.20, p = 0.0017) than women with at least one short allele. The data presented in this study, together with our previously published data, suggest that AP-2beta intron 2 genotype is associated with low levels of anxiety-related personality traits in women. Hence, these data further suggest the human AP-2beta gene as a novel candidate gene in personality.

The DTNBP1 (dysbindin) gene contributes to schizophrenia, depending on family history of the disease.

We have investigated the gene for dystrobrevin-binding protein 1 (DTNBP1), or dysbindin, which has been strongly suggested as a positional candidate gene for schizophrenia, in three samples of subjects with schizophrenia and unaffected control subjects of German (418 cases, 285 controls), Polish (294 cases, 113 controls), and Swedish (142 cases, 272 controls) descent. We analyzed five single-nucleotide polymorphisms (P1635, P1325, P1320, P1757, and P1578) and identified significant evidence of association in the Swedish sample but not in those from Germany or Poland. The results in the Swedish sample became even more significant after a separate analysis of those cases with a positive family history of schizophrenia, in whom the five-marker haplotype A-C-A-T-T showed a P value of.00009 (3.1% in controls, 17.8% in cases; OR 6.75; P=.00153 after Bonferroni correction). Our results suggest that genetic variation in the dysbindin gene is particularly involved in the development of schizophrenia in cases with a familial loading of the disease. This would also explain the difficulty of replicating this association in consecutively ascertained case-control samples, which usually comprise only a small proportion of subjects with a family history of disease.

No association between a putative functional promoter variant in the dopamine beta-hydroxylase gene and schizophrenia.

OBJECTIVE: Disturbances in catecholamine transmission have been implicated in schizophrenia. Dopamine beta-hydroxylase catalyses the conversion of dopamine to norepinephrine in noradrenergic cells. We attempted to investigate a putative functional promoter polymorphism in the dopamine beta-hydroxylase gene (DBH) for association with schizophrenia. METHODS: Unrelated schizophrenic patients (n=155) and control subjects (n=436) were analysed with regard to the DBH -1021 C/T variant. RESULTS: No significant allele or genotype differences were found. CONCLUSIONS: The present results do not support a major involvement of the DBH gene in schizophrenia in the Swedish population investigated.

Association between a promoter dopamine D2 receptor gene variant and the personality trait detachment.

BACKGROUND: Personality traits have shown considerable heritable components. Striatal dopamine D(2) receptor density, as determined by positron-emission tomography, has been associated with detached personality, as assessed by the Karolinska Scales of Personality. A putative functional promoter polymorphism in the dopamine D(2) receptor gene (DRD2), -141C ins/del, has been associated with dopamine D(2) receptor density. METHODS: In this study healthy subjects (n = 235) who filled in at least one of several personality questionnaires (Karolinska Scales of Personality, Swedish Universities Scales of Personality, Health-relevant Five-factor Personality Inventory, and Temperament and Character Inventory) were analyzed with regard to the DRD2 -141C ins/del variant. RESULTS: There was an association (p =.001) between the DRD2 -141C ins/del variant and Karolinska Scales of Personality Detachment scale, indicating higher scores in subjects with the -141C del variant. There were also associations between the DRD2 -141C ins/del variant and a number of Karolinska Scales of Personality and Swedish Universities Scales of Personality Neuroticism-related scales, but of these only Swedish Universities Scales of Personality Lack of Assertiveness scale (p =.001) survived correction for multiple testing. CONCLUSIONS: These results add further support for the involvement of dopamine D(2) receptor in certain personality traits. The results should be treated with caution until replicated.

Association between a promoter variant in the monoamine oxidase A gene and schizophrenia.

Monoaminergic transmission has been implicated in the pathophysiology of schizophrenia. We investigated a putative functional promoter polymorphism in the monoamine oxidase A (MAOA) gene in schizophrenic patients (n=133) and control subjects (n=377). In men, there was an association between the less efficiently transcribed alleles and schizophrenia (chi(2)=4.01, df=1, p<0.05). In women, no significant differences were found. The present results support the involvement of the MAOA gene in men with schizophrenia in the investigated Swedish population but should be interpreted with caution until replicated.

Dopamine D3 receptor gene Ser9Gly variant and schizophrenia: association study and meta-analysis.

OBJECTIVE: To further evaluate the controversial putative association between a Ser9Gly variant in the first exon of the dopamine D3 receptor gene (DRD3) and schizophrenia. METHODS: Swedish patients with schizophrenia ( n=156) and control subjects ( n=463) were assessed for the DRD3 Ser9Gly variant. Meta-analyses including previous and the present Swedish case-control results were performed. RESULTS: No significant difference between the Swedish patients and controls were found, but there was an association between DRD3 Ser9Gly Ser/Ser and homozygous genotypes and response to anti-psychotic drugs. This finding was supported by an incomplete meta-analysis. In a meta-analysis of all case-control studies comprising 8761 subjects the association between DRD3 Ser9Gly homozygosity and schizophrenia ( =4.96, degree of freedom=1, p <0.05, odds ratio=1.10, 95% confidence interval=1.01-1.20) persisted. However, the previously proposed association between the Ser/Ser genotype and schizophrenia was not significant (chi2 =2.71, degree of freedom=1, p>0.05, odds ratio=1.08, 95% confidence interval=0.99-1.17). CONCLUSIONS: Whereas the present Swedish case-control analysis did not yield any evidence for association with the diagnosis, the present meta-analysis suggests that the DRD3 gene confer susceptibility to schizophrenia. Reasons for the discrepancies between prior studies are discussed.

Association study between dopamine D3 receptor gene variant and personality traits.

Dopamine receptor gene variation has been hypothesized to influence personality traits characterized by novelty seeking and related traits. We analyzed a dopamine D(3) receptor gene (DRD3) variant in a Swedish population (n = 373) investigated with one or more of several personality questionnaires. No significant relationships were found between DRD3 genotypes and any of the 15 Karolinska Scales of Personality (KSP) and five Health-relevant Personality 5 factor inventory (HP5i) scales. The DRD3 variant was associated with some scales related to novelty seeking: the Swedish universities Scales of Personality (SSP) Adventure Seeking and the revised NEO personality inventory (NEO-PI-R) Fantasy (O1) and Order (C2) scales. There were also associations with the Temperament and Character Inventory (TCI) Cooperativeness and Compassion (C4) scales. After correction for multiple testing, however, no significant difference remained. We conclude that the investigated DRD3 polymorphism does not have a major impact on personality in the investigated population.

No association between a transcription factor Activating Protein 2beta (AP-2beta) gene variant and schizophrenia.

Genetic components are involved in the aetiology of schizophrenia. Activating Protein 2 (AP-2) transcription factors are essential for neural gene expression and neural development. Transcription factor AP-2beta has also been connected with monoaminergic genes and monoamine levels in various brain regions. Thus, the AP-2beta gene is a suitable candidate taking both the neurodevelopmental and dopamine hypotheses of schizophrenia into account. We investigated 135 schizophrenic patients and 382 control subjects with regard to an intronic AP-2beta variant without evidence of any association. We conclude that the investigated AP-2beta variant is not of major importance to schizophrenia in the investigated Swedish population.

A regulatory monoamine oxidase a promoter polymorphism and personality traits.

Monoamine oxidase type A (MAOA) has been implicated to be part of mechanisms underlying human temperament and psychiatric disorders. We hypothesised that a functional polymorphism in the 5' untranslated region of the MAOA gene is associated with specific personality traits. In 371 healthy Caucasians, we estimated personality traits by the use of the Karolinska Scales of Personality (KSP), Scandinavian Universities Scales of Personality, Health-Relevant 5-Factor Personality inventory, Temperament and Character Inventory and the revised NEO Personality Inventory. In the same subjects, we analysed the genotype of a polymorphic region consisting of a variable number of a 30-bp repeat sequence located approximately 1.2 kb upstream of the MAOA gene. After correction for multiple testing, no statistically significant differences between MAOA genotype and personality were observed in men (n = 206) nor in women (n = 165). We conclude that the structure of this MAOA promoter region does not have a large impact on the expression of personality characteristics in the present Swedish population.