In addition, the Alzheimer's disease Aβ peptide, the prion protein (PrPc), as well as Cu/Zn-superoxide dismutase, are each regulated by binding to copper, have well documented roles in modulating synaptic plasticity, and could be part of a set of copper-interacting proteins that influence the deterioration of learning and memory in neurodegenerative diseases [46–49]. This evidence concerns the gene PRNP and neurodegenerative disease.