An association study between various monoamine transporter gene polymorphisms and treatment response to mirtazapine in major depression

Background

Genetic differences may contribute to the inter-individual differences in treatment response to antidepressants among patients suffering from major depression. This study investigated a possible association of various monoamine transporter genetic polymorphisms with treatment response to mirtazapine in major depressive patients in elderly.

Materials and methods

In this study, three genetic polymorphisms were selected: serotonin transporter 5-HTTLPR, serotonin transporter 5-HTT intron 2 VNTR, and norepinephrine transporter NET(G1287A). The patients with major depression diagnosed by DSM-IV were recruited to a 6-week naturalistic mirtazapine treatment study in Samsung Medical Center. Treatment response to mirtazapine was defined as ≥50% decrease in HAMD-17 scores at 6 weeks, and the genotypes in the patients were determined using the polymerase chain reaction.

Results

Our results showed that ss allele carriers were included more in responder group(ss allele in responder vs. non responder group; 69.4% vs. 40.0%). In addition, l-allele (sl/ll) carriers were included less in responder group(sl/ll allele in responder vs. non responder group; 30.6% vs. 60.0%). Multiple logistic regression analyses showed the 5-HTTLPR polymorphism as an predictor of the mirtazapine response (5HTTLPR ss allele carrier vs. l-allele (sl/ll) carrier; odds ratio: 3.81; 95% confidence interval [CI], 1.32-11.0; P = 0.013). However, 5-HTT intron 2 VNTR l/s (P = 0.33 by multiple logistic regression; [OR], 0.53; 95% [CI], 0.15-1.88), and NET(G1287A) G/A (P = 0.68 by multiple logistic regression; [OR], 1.25; 95% [CI], 0.44-3.53) showed no statistical significant influences on response rate.

Conclusions

In conclusion, 5HTTLPR polymorphism may predict treatment response to mirtazapine in major depressive patients in elderly.