Collectively, PrP sequence conservation analysis has shown that, in addition to the well-established scrapie-susceptibility associations of amino acid residues 136 and 171, Met132 at the start of β-strand-1; His143; Met157 in helix-1; and the helix-2-helix-3 loop region may be required for the structural stability of the prion protein or are involved in hitherto unidentified molecular interactions, for example, oligomeric formation. The gene discussed is PRNP; the disease is scrapie.