PRND and Ataxia: We previously reported that Prnp0/0 mice used in this study developed cerebellar ataxia at 469±46 days after birth due to ectopic expression of a PrP-like molecule Dpl in their brains [12], [14], and that the ataxia was not rescued in Tg(MHM2Δ23-88)/Prnp0/0 mice [11].