PRNP and cerebellar ataxia: In prion diseases, genetic mutations of PrPC induce spongiform encephalopathy and spontaneous neurodegeneration, and the disease-associated mutations of PrPC lead to severe ataxia, apoptosis, and extensive central and peripheral myelin degeneration.55, 56 As shown in this study, overexpression of the disease-associated mutants of PrPC (P102L and MΔ8) impaired neurite outgrowth because of the failure to inactivate RhoA and reduced the co-immunoprecipitation of RhoA and p190RhoGAP.