The small size of the peptides obtained from the proteolytic digestion of the most barostable/compact M109I fibril is congruent with previous studies showing a lower molecular weight PK-resistant PrP fragment in the brains of in spontaneously ill transgenic mice overexpressing bank vole PrP with the M109I polymorphism35, compared to the brains of FFI and CJD(E200K) patients. The gene discussed is PRNP; the disease is Creutzfeldt Jacob disease.