Quinolinic acid (a downstream metabolite of tryptophan), induced via IDO-1 (Heyes et al., 1992), has been associated with a variety of inflammatory disorders, elevated, and also detected in elevated concentrations in the CSF and brain tissue of patients with a wide range of infectious and other neurological diseases (Heyes et al., 2001), produced in large quantities by activated macrophages and microglia (Heyes et al., 1996). The gene discussed is IDO1; the disease is nervous system disorder.