No association between the TPH A218C polymorphism and personality traits in Japanese healthy subjects

Relationships of Ischemic Stroke Occurrence and Outcome with Gene Variants Encoding Enzymes of Tryptophan Metabolism

Ischemic stroke is among the leading causes of mortality and long-term disability worldwide. Among stroke risk factors the importance of genetic background is gaining interest. There is a growing body of evidence of changes of metabolite levels and enzyme activities involved in the conversion of Trp during the course of cerebral ischemia. We compared the frequencies of ten SNPs of five genes related to Trp metabolism between groups of 122 ischemic stroke patients and 120 control individuals. Furthermore, we examined the mRNA levels of TPH1, IDO1 and KYAT1 genes in peripheral venous blood with the aim of assessing (i) whether there are changes in their expression during the course of stroke and (ii) does any of their investigated SNPs have an impact on gene expression. In seven cases out of ten studied polymorphisms we detected significant differences in frequencies in relation to ischemic stroke occurrence, etiology, and clinical parameters. We also detected changes in the expression of TPH1 and IDO1 genes during the course of the disease. We found that those IDO1 variants which show a trend towards elevated mRNA level are more frequent in stroke patients than in controls. Our results are important novel observations which suggest a causal relationship between elevated IDO1 expression and stroke etiology.

TPH1 A218C polymorphism and temperament in major depression

BACKGROUND

In major depression, one of the candidate genes possibly affecting the risk and severity of symptoms has been found to be tryptophan hydroxylase (TPH1). Variation in treatment response to antidepressive agents according to TPH1 genotype has also been found in several studies. However, the relationship between temperament and TPH1 genotype in major depression is poorly understood, as only one study has been published so far. There are no earlier studies on the interaction between temperament traits, antidepressive medication response and TPH1 genotype. This interaction was studied in 97 subjects with major depression treated for six weeks with selective serotonine reuptake inhibitors.

METHODS

Temperament dimensions Harm Avoidance (HA), Novelty Seeking (NS), Reward Dependence (RD) and Persistence (P) scores at baseline (1) and endpoint (2) were rated with the Temperament and Character Inventory (TCI) and compared between TPH1 A218C genotypes. Multivariate analysis of co-variance (MANCOVA) was used to analyze the interaction between the TPH1 genotype, treatment response and the different temperament dimensions at baseline and endpoint. In the analysis model, treatment response was used as a covariate and TPH1 genotype as a factor. A post hoc analysis for an interaction between remission status and TPH1 A218C genotype at endpoint HA level was also performed.

RESULTS

The number of TPH1 A-alleles was associated with increasing levels in NS1 and NS2 scores and decreasing levels in HA1 and HA2 scores between TPH1 A218C genotypes. In the MANCOVA model, TPH1 genotype and treatment response had an interactive effect on both HA1 and HA2 scores, and to a lesser degree on NS2 scores. Additionally, an interaction between remission status and TPH1 A218C genotype was found to be associated with endpoint HA score, with a more marked effect of the interaction between CC genotype and remission status compared to A-allele carriers.

CONCLUSIONS

Our results suggest that in acute depression TPH1 A218C polymorphism and specifically the CC genotype together with the information on remission or treatment response differentiates between different temperament profiles and their changes.

Brain Modules, Personality Layers, Planes of Being, Spiral Structures, and the Equally Implausible Distinction between TCI-R "Temperament" and "Character" Scales: A Reply to Cloninger

In this reply we address comments by Cloninger (this issue) related to our report (Farmer & Goldberg, this issue) on the psychometric properties of the revised Temperament and Character Inventory (TCI-R) and a short inventory derivative, the TCI-140. Even though Cloninger's psychobiological model has undergone substantial theoretical modifications, the relevance of these changes for the evaluation and use of the TCI-R remains unclear. Aspects of TCI-R assessment also appear to be theoretically and empirically incongruent with Cloninger's assertion that TCI-R personality domains are non-linear and dynamic in nature. Several other core assumptions from the psychobiological model, including this most recent iteration, are non-falsifiable, inconsistently supported, or have no apparent empirical basis. Although researchers using the TCI and TCI-R have frequently accepted the temperament/character distinction and associated theoretical ramifications, for example, we find little overall support for the differentiation of TCI-R domains into these two basic categories. The implications of these observations for TCI-R assessment are briefly discussed.

Association study of catechol-O-methyltransferase Val158Met polymorphism with personality traits in japanese healthy volunteers

Catechol-O-methyltransferase (COMT) is one of the major enzymes for the degradation of catecholamines. It has been suggested that catecholaminergic neurotransmission is involved in characterization of personality. Previous studies on the association between the COMT Val158Met polymorphism and personality traits in healthy subjects have produced inconsistent results. Therefore, the relationship between this polymorphism and personality was re-examined in 478 Japanese healthy volunteers. Personality traits were assessed by the Temperament and Character inventory (TCI), and the COMT genotypes were determined by a PCR-RFLP method. in total, there were no significant differences among the Val/Val, Val/Met, and Met/Met genotypes in seven TCI dimension scores. Similarly, no significant relationship was found between the COMT genotypes and the TCI dimensions when males and females were analyzed separately. The present study thus suggests that the COMT Val158Met polymorphism is not associated with personality traits in Japanese healthy subjects.