Early response to selective serotonin reuptake inhibitors in panic disorder is associated with a functional 5-HT1A receptor gene polymorphism

Background: Panic disorder is a common and disabling condition which can be treated with selective serotonin reuptake inhibitors (SSRIs). Although many subjects respond well to such treatment, there is substantial inter-individual variation implicating genetic factors. Methods: 102 patients with a diagnosis of panic disorder receiving sertraline or paroxetine took part in study. Hospital Anxiety and Depression Scale score, CGI and panic attack frequency (per month) were assessed before and after 6 weeks of SSRI treatment with 1 week of titration period. All patients were genotyped for the - 1019C/G 5-HT1A receptor and ins/del 5-HT transporter polymorphisms. Results: The 5-HT1A receptor - 1019C/G polymorphism was strongly associated with response to treatment, in which 20 subjects with the GG genotype showed minimal changes in panic attack frequency with a relative risk of no response of 4.73. This association was also found with each drug independently. However, no association of the ins/del 5-HT transporter polymorphism with treatment response was observed. Limitations: Larger numbers of subjects and longer period of SSRI treatment would confirm and strengthen these preliminary findings. Conclusion: These results indicate the importance of a 5-HT1A receptor gene polymorphism in the response to SSRI treatment of panic disorder. (C) 2009 Elsevier B.V. All rights reserved.