Notably, however, both human PrP 200K-129M-expressing lines Tg23 and Tg49 propagated PrPSc with a slightly lower molecular mass fragment size than type 4 PrPSc seen in the vCJD inoculum (Fig. 1d, lanes 4 and 5). Here, PRNP is linked to variant Creutzfeldt-Jakob disease.