AβO binds to the huPrP N-terminus15–19, which triggers a neurotoxic signaling cascade that may be responsible for early synaptic dysfunction in AD, involving metabotropic glutamate receptor 5 (mGluR5), Fyn kinase, and N-methyl-d-aspartate (NMDA) receptors20,21. Here, ABO is linked to Alzheimer disease.