Anfinsen's dogma
Prions are an exception to Anfinsen's dogma. Prions are stable conformations of proteins which differ from the native folding state. In Bovine spongiform encephalopathy (Mad Cow Disease), native proteins re-fold into a different stable conformation, which causes fatal amyloid buildup. Other amyloid diseases, including Alzheimer's disease and Parkinson's disease, are also exceptions to Anfinsen's dogma.