Propagation of type 4 PrPSc in these mice is often accompanied by the key neuropathological hallmark of vCJD, the presence of abundant florid PrP plaques in the cortex and other brain regions, which are frequently seen on a strong background of synaptic PrP deposition [7–9,23,24]. The gene discussed is PRNP; the disease is variant Creutzfeldt-Jakob disease.