PRNP and demyelinating polyneuropathy: Thirdly, both a hemizygous Prnp allele and the tga20 transgene was found to suppress both the granule-cell degeneration of Dpl-overexpressing mice and the chronic demyelinating peripheral neuropathy of Prnp-/- mice[63, 64], indicating that the tga20 allele is functionally indistinguishable from its wild-type counterpart.