Lack of relationship between CO 2 reactivity and serotonin transporter gene regulatory region polymorphism in panic disorder

Changes in the function of the serotonergic system influence both panic phobic symptoms and carbon dioxide (CO 2 ) reactivity in patients with panic disorder. Schmidt et al. [2000: J Abnorm Psychol 109(2):308–320] recently reported a predictive role of the genetic variants of the 5‐HTTLPR on the fearful response to CO 2 in healthy controls. We tested the hypothesis that the heterogeneity of CO 2 reactivity in patients with panic disorder could be related to the allelic variation of the 5‐HTT promoter. Ninety‐five patients with panic disorder were challenged with 35% CO 2 . 5‐HTTLPR allelic variation in each subject was determined using a PCR‐based method. There were no differences for all the measures of CO 2 reactivity among the genotype groups. CO 2 reactivity of patients with panic disorder seems not to be influenced by the genetic variants of the 5‐HTTLPR; this finding does not support a role for the serotonin transporter in the etiopathogenesis of CO 2 reactivity in panic disorder. © 2004 Wiley‐Liss, Inc.