Patients with a clinical Parkinsonism in life and neuropathological confirmation of Corticobasal Degeneration (CBD) were identified from brain banks, research hospitals and neuropathologists. The top three contributing sites were the Mayo Clinic, University College London, and the University of Pennsylvania and additional small numbers of cases were obtained from various other institutions across the US and some international collaborators. 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.