Relationship between the serotonin receptor 1A polymorphism with treatment response to escitalopram in patients with major depresive disorder

Objective: Serotonin 1A receptor (HTR1A) is a candidate molecule for influencing the pathophysiology of major depressive disorder (MDD) and clinical responses to antidepressant treatment. Among polymorphisms of the HTR1A gene, -1019C>G (rs6295) is reportedly a biologically functional polymorphism associated with response to antidepressant treatment. The aim of this study was to determine the relationship between the HTR1A-1019C>G polymorphism and the response to escitalopram in patients with MD. Method: Eighty Korean patients were examined using the Structured Clinical Interview for DSM-IV Axis I disorders and took escitalopram at a daily dose of 5 to 40 mg. Clinical symptoms were evaluated using the 21-item Hamilton Depression Rating (HAM-D) scale during 8 weeks of treatment. The genotypes were determined using HpyCH4 IV digestion following polymerase chain reaction. Results: The proportion of G-allele carriers was 25.0% in responders, which was lower than that in non-responders (53.9%) at 1 week of escitalopram treatment (OR = 0.28, P = 0.030). In allelic analysis, the frequency of the G allele was significantly lower in responders at 1 week than in non-responders (12.5% versus 31.7%, respectively; OR = 0.29, P = 0.029). Similarly, the ratio of HAM-D score at 1 week to the baseline score in C-allele carriers was 67.6% ± 2.42%, which was significantly lower than the ratio of 75.8% ± 2.74% in patients possessing the G allele (P = 0.027). Conclusions: Although this study is preliminary and has several limitations, our results suggest that HTR1A- 1019C>G may be a genetic marker predicting the response to escitalopram treatment.