PRNP and human prion disease: While PrP is notorious for its association with the transmissible spongiform encephalopathies such as Creutzfeldt Jacob Disease and Bovine Spongiform Encephelopathy (Mad Cow Disease) it has become clear in recent years that PrP has a range of normal functions, including in neurogenesis and neural plasticity (Kanaani et al. 2005; Moya et al. 2005; Santuccione et al. 2005; Steele et al. 2006).