KMO and Huntington disease: Kynurenine 3-monooxygenase (KMO), a pivotal enzyme in the kynurenine pathway (KP) oftryptophan degradation, has been suggested to play a critical role inHuntington’s (HD) and Alzheimer’s diseases (AD)6, 7, 8.It is widely distributed in peripheral tissues, including liver and kidney, and inphagocytes such as macrophages and monocytes9, 10, and also in microglialcells in central nervous system11, 12.