Background: Polymorphisms in the monoamine oxidase A (MAOA) gene may influence treatment outcomes in major depression disorder (MDD).
Objective: To investigate the association of MAOA genetic polymorphisms and response to mirtazapine in patients with MDD.
Method: Fifty-eight adult patients in Taiwan who met the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) diagnostic criteria for MDD were given mirtazapine for 7 weeks and evaluated on days 0, 7, 14, 21, 49 using the 24-item Hamilton Rating Scale for Depression (HRSD). Remission was defined as a final HRSD <or= 10 and a 50% reduction in baseline HRSD score. Patients provided venous blood for DNA testing. The patients' response to mirtazapine treatment was compared between those who had the long-form polymorphism in the MAOA gene promoter and the short-form polymorphism.
Result: The total HRSD scores after mirtazapine treatment were significantly lower than baseline (p < 0.001). There were 10 cases (38.5%) in short from and 6 (18.8%) in long from group touched the remission stage. Patients with the short-form group had a greater response to mirtazapine (p < 0.001) than those with the long-form polymorphism after controlling for age, sex, and apolipoprotein E genetic (APOE) polymorphism.
Conclusion: The genetic polymorphisms in the MAOA promoter region may be associated with treatment response to mirtazapine.