Novel 5'-regulatory region polymorphisms of the 5-HT2C receptor gene: association study with panic disorder.

Candidate genes for association studies in panic disorder are often selected on the basis of molecular mechanisms of drugs utilized in challenge tests such as m-chlorophenylpiperazine (mCPP), a non-selective 5-HT2C receptor agonist. Two novel, adjacent polymorphisms [(GT)12-18 and (CT)4-5] in the 5'-regulatory region of the X-chromosomal 5-HT2C receptor gene have recently been reported. We determined the allele frequency of long vs. short polymorphism haplotypes in a German and an Italian sample (combined n = 211) of panic disorder patients (DSM-III-R) and compared it with allele frequencies in two ethnically matched control samples (combined n = 226). In the German sample, a comparison of female genotypes containing the short haplotype vs. female genotypes containing only long haplotypes showed a significant difference (p = 0.01, ?2 analysis). In the Italian sample, however, this observation could not be replicated (p = 0.54, ?2 analysis). This argues against a major role for these promoter-associated 5-HT2C receptor gene length polymorphisms in the aetiopathogenesis of panic disorder.