MPO (Myeloperoxidase) is a member of the peroxidase family, primarily produced by neutrophils and located in the azurophilic granules of white blood cells. MPO plays a key role in immune defense by catalyzing the production of highly oxidizing compounds, contributing to the killing of bacteria and fungi. Additionally, MPO is involved in regulating inflammatory responses and promoting the process of atherosclerosis. The expression level and functional mutations of the MPO gene are associated with the development of various diseases, including cardiovascular diseases, chronic inflammatory diseases, and certain forms of cancer.