Moreover, the protein content of ferroportin—the only known transmembrane protein that transports iron out of the cell—is reduced with age in an AD model and in AD patients, and ferroportin knockout causes hippocampal atrophy and memory impairments in mice [8]; these results imply an important role for iron dysregulation and ferroptosis in hippocampal-related diseases. This evidence concerns the gene SLC40A1 and Alzheimer disease.