TPH2 Gene

Because serotonin is critical to so many processes in the central nervous system, genes involved in its synthesis are interesting to neuroscientists.

Tryptophan hydroxylase 2 (TPH2) is a rate-limiting enzyme involved in the synthesis of serotonin (rate-limiting enzymes control the rate of activity in biochemical reactions). Because serotonin is critical to so many processes in the central nervous system, genes involved in its synthesis are interesting to neuroscientists. TPH2 has attracted attention as a component of the serotonin hypothesis of depression. It is expressed primarily in brain tissue. A study by Cichon and colleagues (2008) identified a rare single nucleotide polymorphism in the TPH2 gene that resulted in a proline-serine substitution at position 206 (P206S), which significantly correlated with bipolar disorder. Zhang and colleagues (2005) found that a rare TPH2 mutation was significantly more common in a group of individuals with depression. Excitement at this discovery, however, has been tempered by a failure to replicate the finding in a number of follow-up studies.