Prion diseases, or transmissible spongiform encephalopathies (TSEs), are manifested as genetic, infectious or sporadic lethal neurodegenerative disorders involving alterations of the prion protein (PrP). Constitutively expressed in normal adult brain, cellular PrP (PrP(C)) is sensitive to proteinase K digestion and is converted to the disease form, PrPSc, through alterations in protein folding conformation, which make it resistant proteases. SPRN (shadow of prion protein), also known as SHO or SHADOO, is a 151 amino acid cytoplasmic protein that is mainly expressed in brain. SPRN is considered a prion-like protein that has PrP(C)-like neuroprotective activity and may act as a modulator for the biological actions of normal and abnormal PrP. In humans, mutations in the gene encoding SPRN may be associated with variant and sporadic Creutzfeldt-Jakob disease, a degenerative neurological disorder that is incurable and invariably fatal