PRNP and cerebellar ataxia: GSS-related PRNP mutations include, P102L, P105L, A117V, Q160X, F198S, Q217R, Y218N, Y226X and Q227X, among which P102L is the most common.7,8 Patients with the P102L mutation are characterized with cerebellar ataxia, and can have predominant psychiatric symptoms such as apathy and depression, which is consistent with our case.