Infections led to Aβ deposition and increased PrPC and then caused high affinity binding between Aβ oligomers and PrPC, finally activated the Fyn signaling cascade, resulting in neuron death in brain of AD (Guerrero-Muñoz et al., 2014; Kodidela et al., 2019; Zhang B. et al., 2020). This evidence concerns the gene PRNP and Alzheimer disease.