The FPi function proved to be an effective tool to investigate conformational behavior of the intrinsically disordered and pleiomorphic proteins, revealing a common pattern of backbone density distribution in the amyloidogenic regions of several highly pleiomorphic proteins associated with neurodegenerative diseases: amyloid beta Aβ, tau, α-synuclein αS, and mammalian prions PrPC. The gene discussed is MAPT; the disease is neurodegenerative disease.