Common Genetic Polymorphisms in the ABCB1 Gene Are Associated with Risk of Major Depressive Disorder in Male Portuguese Individuals

Major depressive disorder (MDD) is a highly prevalent disorder, which has been associated with an abnormal response of the hypothalamus–pituitary–adrenal (HPA) axis. Reports have argued that an abnormal HPA axis response can be due to an altered P-Glycoprotein (P-GP) function. This argument suggests that genetic polymorphisms in ABCB1 may have an effect on the HPA axis activity; however, it is still not clear if this influences the risk of MDD. Our study aims to evaluate the effect of ABCB1 C1236T, G2677TA and C3435T genetic polymorphisms on MDD risk in a subset of Portuguese patients. DNA samples from 80 MDD patients and 160 control subjects were genotyped using TaqMan® SNP Genotyping assays. A significant protection for MDD males carrying the T allele was observed (C1236T: odds ratio (OR)=0.360, 95% confidence interval [CI]: [0.140–0.950], p=0.022; C3435T: OR=0.306, 95% CI: [0.096–0.980], p=0.042; and G2677TA: OR=0.300, 95% CI: [0.100–0.870], p=0.013). Male Portuguese individuals carrying the 1236T/2677...