, and Genetic Polymorphisms and Antidepressant Response Phenotypes: Results from a Portuguese Major Depressive Disorder Cohort.

P-glycoprotein (P-GP) is a transporter molecule expressed on the apical surface of capillary endothelial cells of the Blood-Brain Barrier (BBB), whose activity heavily influences drug distribution, including antidepressants. This transporter is encoded by gene, and genetic variations within gene have been proposed to affect drug efflux and have been previously associated with depression. In this context, we aimed to evaluate the role of , and genetic polymorphisms in antidepressant treatment phenotypes from a cohort of patients harboring Major Depressive Disorder. Patients enrolled in the study consisted of 80 individuals with Major Depressive Disorder, who took part in a 27-month follow-up study at HML, Portugal. To investigate the correlation between polymorphisms and antidepressant response phenotypes, DNA was extracted from peripheral blood, and , and polymorphisms were genotyped with TaqMan SNP Genotyping Assays. Despite the fact that the evaluated polymorphisms (, and ) were not associated with treatment resistant depression, or relapse, we observed that patients carrying TT genotype of the polymorphism remit earlier than the ones carrying CC or CT genotypes (10.2 weeks vs. 14.9 and 21.3, respectively, = 0.028, Log-rank test). Since we found an association with and time to remission, and not to the absence of remission, we suggest that this polymorphism could have an impact on antidepressant drug distribution, and thus influence on the time to remission will occur, without influencing the risk of remission itself.