GRN and primary progressive aphasia: Extrapyramidal features have been previously described in GRN mutations (in up to 40–60% of patients37,38), and people with overlapping syndromes of PPA and CBS have also been seen, but PSP is not a syndrome seen in GRN mutations.39 The less frequent occurrence of motor features and full-blown parkinsonian syndromes (particularly PSP) appears to be a distinct feature of the GRN nfvPPA form.