Tg(Mo/Hu-PrP-E199K) mice, which express mouse-human chimeric PrP, or Mo/Hu-PrP, with the E199K mutation (the human homologue of E200K in fCJD) 2 times higher than PrPC in WT mice, were reported to develop neurological disease around 200 days of age, with hind-limb paralysis and kyphosis (Table 1) [63]. Here, PRNP is linked to nervous system disorder.