GRN and Aphasia: Disorders that broadly resemble PSP can arise from mutations in C9orf72 (overlapping with frontotemporal dementia, motor neurone disease, aphasia, ataxia), microtubule associated protein tau (overlapping frontotemporal dementia, CBS), progranulin (GRN, overlapping frontotemporal dementia, aphasia), Park9 (Kufor-Rakeb syndrome) and CSF-1R (hereditary leukoencephalopathy with axonal spheroids) among others.