PRNP and Parkinson disease: Although case reports have linked parkinsonism with DAT-SPECT in sporadic CJD, fatal familial insomnia (FFI), GSS F198S [GSS caused by a serine (S) substitution of phenylalanine (F) at position 198 of the prion protein gene (PRNP)], and GSS D202N [GSS caused by a asparagine (N) substitution of aspartic acid (D) at position 202 of the PRNP] (9–11), the assessment of dopaminergic function in GSS P102L remains unknown.