Four single nucleotide polymorphisms (SNPs) in the TPH1 gene and one SNP in the TPH2 gene were selected based on previous studies investigating associations between these SNPs and psychiatric or behavioral disorders.
Although the predominant role of tryptophan hydroxylase 2 (TPH2) in the CNS and its influence on the vulnerability to psychiatric disorders have clearly been demonstrated in several studies, the role of TPH1 on neuronal mechanisms, respectively on behavioral traits is still poorly understood.
They underwent a blood sample collection for A218C polymorphism of the tryptophan-hydroxylase-1 genotyping and a clinical evaluation assessing comorbidity for Axis I and II psychiatric disorders, harm avoidance personality dimension and bulimic symptoms.
We found the haplotype TCAAA of -7180/-7065/-6526/218/779 to be strongly associated with suicidal behaviour and psychiatric disorders (p = 0.00243; OR = 1.62; 95% CI 1.17 to 2.24 and p = 0.018; OR = 1.41; 95% CI 1.05 to 1.91), which suggests an association of TPH1 with suicidal behaviour and indicates that TPH1 may play a significant role in the aetiology of psychiatric disorders in the Han Chinese population.
Therefore, contribution of TPH1 to brain 5-HT levels is not known, and the mechanisms how TPH1 possibly contributes to the pathogenesis of psychiatric disorders are not understood.
Analysis of these different polymorphisms will constitute an important tool for future studies between the TpH gene and psychiatric disorders.Molecular Psychiatry (2000) 5, 49-55.