Functional polymorphism of the GTP cyclohydrolase 1 gene affects the personality trait of novelty seeking in healthy subjects

Taking risks to feel excitement: Detailed personality profile and genetic associations

This study mapped the personality and genetics of risky excitement-seekers focusing on skydiving behavior. We compared 298 skydivers to 298 demographically matched controls across the NEO Personality Inventory-3 domains, facets, and 240 items. The most significant item-level effects were aggregated into a poly-item score of skydiving-associated personality markers (Study 1), where higher scores describe individuals who enjoy risky situations but have no self-control issues. The skydiving-associated personality marker score was associated with greater physical activity, higher rate of traumatic injuries, and better mental health in a sample of 3558 adults (Study 2). From genetic perspective, we associated skydiving behavior with 19 candidate variants that have previously been linked to excitement-seeking (Study 1). Polymorphisms in the SERT gene were the strongest predictors of skydiving, but the false discovery rate-adjusted (FDR-adjusted) p-values were non-significant. In Study 2, we predicted the skydiving-associated personality marker score and E5: Excitement-seeking from multiple risk-taking polygenic scores, using publicly available summary data from genome-wide association studies. While E5: Excitement-seeking was most strongly predicted by general risk tolerance and risky behaviors’ polygenic scores, the skydiving-associated personality marker score was most strongly associated with the adventurousness polygenic scores. Phenotypic and polygenic scores associations suggest that skydiving is a specific—perhaps more functional—form of excitement-seeking, which may nevertheless lead to physical injuries.

Implication of P-glycoprotein in formation of depression-prone personality: association study between the C3435T MDR1 gene polymorphism and interpersonal sensitivity

BACKGROUND AND AIM

Interpersonal sensitivity is defined as undue and excessive awareness of, and sensitivity to, the behavior and feelings of others. Previous studies suggested that interpersonal sensitivity is one of the vulnerable factors to depression, and that genetic factors and cortisol are involved in the formation of interpersonal sensitivity. On the other hand, P-glycoprotein, which is encoded by the multidrug resistance 1 (MDR1) gene, serves as a barrier to entry and as an active eliminator for xenobiotics and cellular metabolites including cortisol, which is implicated in multiple brain functions. In the present study, we examined the effects of the MDR1 C3435T polymorphism (rs1045642) on interpersonal sensitivity in healthy subjects.

METHODS

The subjects were 842 healthy Japanese volunteers (mean age = 26.7 years, male/female ratio = 490/352). The C3435T polymorphism of MDR1 gene was detected by a PCR method, and interpersonal sensitivity was assessed by the Interpersonal Sensitivity Measure (IPSM).

RESULTS

The 2-factor analysis of covariance (ANCOVA) showed a significant main effect of the MDR1 genotype on the IPSM scores with a significant interaction between the genotype and gender. The subsequent 1-factor ANCOVA showed that in females the C/C genotype group had higher IPSM scores than the C/T genotype group (p < 0.001) and the T/T genotype group (p < 0.001), and the C/T genotype group had higher IPSM scores than the T/T genotype group (p = 0.014). In males no significant association was found between the MDR1 genotype and the IPSM scores. In allelic analyses using the χ(2) tests, the C allele frequency in females was significantly higher (p < 0.001) in the high IPSM group than in the low IPSM group, while there was no significant difference in the C allele frequency between the high and low IPSM groups in total subjects and males.

CONCLUSION

The present study suggests that the C3435T polymorphism of the MDR1 gene affects the formation of a depression-prone personality trait in Japanese females.

A functional polymorphism of the GTP cyclohydrolase 1 gene predicts attention performance

Guanosine triphosphate cyclohydrolase 1 (GCH1) is the rate-limiting enzyme for the biosynthesis of tetrahydrobiopterin, a cofactor for aromatic amino acid hydroxylases and nitric oxide synthases. As monoamine neurotransmitters are synthesized by the reactions catalyzed by tyrosine hydroxylase and tryptophan hydroxylase, alterations in the content of tetrahydrobiopterin affect the monoamine levels in the brain. Here, we examined the possible association of a functional single-nucleotide polymorphism (SNP) of the GCH1 gene, rs841 (C+243T), with attentional function as assessed by the Continuous Performance Test-Identical Pairs version (CPT-IP) in healthy individuals. We found that homozygous T/T genotype carriers of rs841 scored lower performance on the CPT-IP test. Our data suggest that alterations in GCH1 activity affect attentional function, especially sustained attention and vigilance.

The vitreous, the retinal interface in ocular health and disease

The vitreous is a complex structure whose composition and appearance change with age. Anomalous adhesions between the posterior vitreous face and the retinal surface are the cause of numerous vitreoretinal complications, while the presence of an intact posterior hyaloid provides a scaffold for vascular growth and anteroposterior traction. This review summarizes what is known about the biochemistry of the vitreous, the process of posterior vitreous detachment (PVD) development, and the available clinical approaches to examining the vitreous and its interface. A pooled analysis of studies looking at the presence of a complete, partial or absent PVD in a number of macular and retinal diseases allows us to establish odds ratios for these various states. From this emerge both protective and disease-associated states in conditions such as proliferative diabetic retinopathy, macular edema, and age-related macular degeneration. With the emergence of pharmacological means to separate the posterior hyaloid, a better understanding of the possible role of the vitreous in tractional syndromes is required.