High iron concentrations in the brains of patients and the discovery of mutations in the genes associated with iron metabolism in the brain suggest that iron misregulation in the brain plays a part in neuronal death in some neurodegenerative disorders, such as Alzheimer's, Parkinson's, and Huntington's diseases and Hallervorden-Spatz syndrome. Iron misregulation in the brain may have genetic and non-genetic causes. The disrupted expression or function of proteins involved in iron metabolism increases the concentration of iron in the brain. Disturbances can happen at any of several stages in iron metabolism (including uptake and release, storage, intracellular metabolism, and regulation). Increased brain iron triggers a cascade of deleterious events that lead to neurodegeneration. An understanding of the process of iron regulation in the brain, the proteins important in this process, and the effects of iron misregulation could help to treat or prevent neurodegenerative disorders.