Genome-wide association studies of placebo and duloxetine response in major depressive disorder.

We investigated variants associated with treatment response in depressed patients treated with either the antidepressant duloxetine or placebo using a genome-wide approach. Our sample (N=391) included individuals aged 18-75 years, diagnosed with major depressive disorder and treated with either duloxetine or placebo for up to 8 weeks. We conducted genome-wide associations for treatment response as operationalized by percentage change in Montgomery-Åsberg Depression Rating Scale score from baseline, as well as mixed models analyses across five time points. In the placebo-treated subsample (N=205), we observed a genome-wide association with rs76767803 (ß=0.69, P=1.25 × 10-8) upstream of STAC1. STAC1 rs76767803 was also associated with response using mixed model analysis (χ2=3.95; P=0.001). In the duloxetine-treated subsample (N=186), we observed suggestive associations with ZNF385D (rs4261893; ß=-0.46, P=1.55 × 10-5), NCAM1 (rs2303377; ß=0.45, P=1.76 × 10-5) and MLL5 (rs117986340; ß=0.91, P=3.04 × 10-5). Our findings suggest that a variant upstream of STAC1 is associated with placebo response, which might have implications for treatment optimization, clinical trial design and drug development.

Personality traits as an endophenotype in genetic studies on suicidality in bipolar disorder.

Introduction The influence of personality traits on suicidal behaviour risk has been well documented. Personality traits and suicidal behaviour are partially genetically determined and personality has been described as an endophenotype of suicidal behaviour. The aim of this study was to investigate a possible association between personality traits with suicidal behaviour and selected serotonergic gene polymorphisms. METHODS: In the study we included 156 patients meeting DSM-IV criteria for bipolar disorder (BP) and 93 healthy controls. The personality dimensions were assessed using the Temperament and Character Inventory (TCI). We genotyped two selected polymorphisms of the tryptophan hydroxylase 1 (TPH1) gene (rs1800532 218A>C and rs1799913 779A>C) and polymorphism in the promoter region of serotonin transporter gene (5-HTTLPR, rs25531) related to serotoninergic neurotransmission. Multiple poisson regression, logistic regression and Kruskal-Wallis tests were applied. RESULTS: We found numerous differences between the BP patients and the control group in terms of their TCI dimensions/subdimensions. Significant differences were found between patients with, and without, suicidal attempts in fatigability and asthenia (Ha4), as well as in harm avoidance (Ha). We also found that the interactions between TCI subdimensions (the interaction of disordiness (Ns4) and spiritual acceptance (St3), disordiness (Ns4) and integrated conscience (C5), extravagance (Ns3) and resourcefulness (Sd3)) were significantly contributing for suicidal behaviour risk. We found association between all studied genetic polymorphisms and several TCI dimensions and subdimensions. CONCLUSION: Our results confirm that personality traits are partially determined by genes. Both personality traits and the interactions between temperament and character traits, may be helpful in predicting suicidal behaviour.