PRNP and Ataxia: Loss of body weight (Figure 6B) and ataxia (Table 1), two parameters of disease severity and of cerebellum dysfunction respectively, were also more pronounced in [Prnp+/+ >Prnp-/-] mice than in [Prnp-/- >Prnp+/+] mice (p < 0.05 and 0.01 by Mann-Whitney test).