Gene expression of tryptophan hydroxylase 2 in post-mortem brain of suicide subjects.

The tryptophan hydroxylase isoform-2 gene (TPH2) is located on chromosome 12 and is expressed primarily in brain tissue. While genetic association and mRNA expression studies implicate the tryptophan hydroxylase isoform-1 gene (TPH1) in depression and suicidality, the TPH1 gene is 150-fold less expressed in mouse brain than TPH2. We hypothesized that completed suicide is associated with abnormal TPH2 expression in the brain. TPH2 and beta-actin mRNA levels were measured in post-mortem brain using quantitative real-time PCR. mRNA samples provided by the Stanley Foundation Array Collection were derived from the dorsolateral prefrontal cortex (Brodmann Area 46) of 23 completed suicides and 23 control subjects. There is no difference in the mRNA levels between the suicide group and non-suicide group (p = 0.69). Although greater amounts of TPH2 mRNA were found in the suicide group, this difference was not significant. Further investigation of TPH2 gene expression is needed to clarify the potential role of this gene in the pathophysiology of suicide.