Patients with a clinical Parkinsonism in life and neuropathological confirmation of Progressive Supranuclear Palsy (PSP) were identified from brain banks, research hospitals and neuropathologists. The top three contributing sites were the Mayo Clinic, Harvard Brain Tissue Resource Center at McClean Hospital, and the University of Pennsylvania and additional small numbers of cases were obtained from various other institutions across the US. The neuropathological diagnosis was made according to NINDS neuropathologic diagnostic criteria. DNA was extracted from brain tissue from patients who had consented for brain donation. DNA samples and/or tissue were sent to the University of Pennsylvania for preparation for genotyping.