Additionally, proteins associated with neurodegenerative diseases, such as amyloid-β (Aβ), α-synuclein (αS), and prion protein (PrP), bind several metal ions that can affect the process of aggregation of Aβ and αS, for example, in Parkinson’s disease or Alzheimer’s disease. This evidence concerns the gene PRNP and early-onset autosomal dominant Alzheimer disease.