Background: Variability in antidepressant response is due to genetic and environmental factors. Since SSRIs exert their activity enhancing the serotonin turnover, genes coding for proteins of the serotonin system are key candidates for a possible genetic influence with response to SSRIs. Therefore tryptophan hydroxylase (TPH), the rate-limiting enzyme in the biosynthesis of serotonin in the raphe nuclei could be a candidate. In the present study, we examined the possible association of the TPH1 218A/C polymorphism with response to SSRIs in a sample of Japanese patients with major depression.
Methods: The 21-item Hamilton Rating Scale for Depression (HAM-D) was administered to evaluate depressive symptoms at baseline and bi-weekly over 6 weeks of treatment. All patients were genotyped for the TPH1 218A/C polymorphism.
Results: Repeated-measures analysis of variance of HAM-D score change over time with baseline scores and 5-HTTLPR variants included in the model as covariate showed no significant association of this SNP with treatment response to SSRIs. Furthermore, no significant association of this SNP could be observed with both responder rate at weeks 2, 4 and 6 and intolerance to SSRIs.
Conclusion: The result suggests that 218A/C variants of TPH1 cannot play a major role as predictor of treatment response as well as intolerance in Japanese patients with major depression.
Copyright 2008 S. Karger AG, Basel.