PDE8B and Autosomal dominant striatal neurodegeneration: Mutations in PDE8B (MIM: 603390), a gene highly expressed in the brain and especially in the putamen, causes autosomal-dominant striatal degeneration (ADSD [MIM: 609161]), a disease that clinically manifests with adult-onset parkinsonism.37, 38 Although the reported MRI abnormalities observed in subjects with ADSD are slightly different from those observed in our individuals, it is striking that both diseases are caused by alterations in PDEs, which lead to clearly visible, largely symmetric, striatal MRI signal abnormalities.