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]. Here, PRNP is linked to early-onset autosomal dominant Alzheimer disease.