AA amyloidosis, like prion disease, may be transmissible. Other diseases involving the mammalian prion protein are known. Kuru was the first infectious human prion disease discovered. The infectious agent is a misfolded form of a host-encoded protein called prion (PrP). Most TSEs are sporadic and occur in an animal with no prion protein mutation. A prion (PrP) is a transmembrane cellular protein found widely in eukaryotic cells. Similarly, removing the prion domain from a fungal prion protein inhibits prionogenesis. Specifically, this is determined by the genes coding for the naturally occurring prion proteins. The word "prion" derives from "proteinaceous infectious particle". Immunohistochemistry can be used to demonstrate prion protein accumulation. The physiological function of the prion protein remains poorly understood. All known prion diseases are untreatable and fatal. The PRNP gene provides the instructions to make a protein called the prion protein (PrP). They conduct research at the Broad Institute to develop therapeutics for human prion diseases. The diversity of the conformations may have led to different forms of the prion diseases.