Hypertryptophanemia, also known as familial hypertryptophanemia, is related to major affective disorder 1 and premature ejaculation. An important gene associated with Hypertryptophanemia is TDO2 (Tryptophan 2,3-Dioxygenase), and among its related pathways/superpathways are Metabolism and Regulation of expression of SLITs and ROBOs. Affiliated tissues include cortex and brain, and related phenotypes are increased serum serotonin and hypertryptophanemia