The tryptophan hydroxylase 1 (TPH1) gene spanning 29kbp with 11 exons is mapped to human chromosome 11p15.3-p14. TPH1, is a 444 amino acid protein expressed in the gut, spleen, thymus and also in the pineal gland and the pituitary.
The tryptophan hydroxylase 1 gene (TPH1) catalyzes the synthesis of 5-hydroxytryptophan, which is a precursor to the neurotransmitter serotonin. Variation in the gene expression affects prefrontal cortex activation during response inhibition. Mutation in the TPH1 gene leads to schizophrenia, irritable bowel syndrome (IBS) in women, suicidal behavior and depressive disorders. The encoded protein plays a vital role in regulation of cardiovascular function.