Clinical/Scientific Notes

Autosomal dominant striatal degeneration (ADSD) (MIM 609161) is a rare genetic disease caused by mutation in the PDE8B gene.(1,2) The disease, with onset in the fourth to fifth decade, is characterized by slowly progressive dysarthria, mild parkinsonism but no tremor, brisk deep tendon reflexes, poor response to levodopa treatment, and distinctive brain MRI findings.(1,2) Heterozygous mutations in the PDE8B gene, first identified in a German family,(2) result in loss of protein cyclic nucleotide phosphodiesterase (PDE) function. PDEs are responsible for the breakdown of cyclic nucleotides, cyclic adenosine monophosphate, and cyclic guanosine monophosphate, and play a major role in striatal neuron regulation.(3) The PDE superfamily consists of 11 families (PDE1-PDE11), each of which has 1 to 4 subtypes. Some neuropsychiatric and neurodegenerative diseases, including depression, schizophrenia, Parkinson disease, Alzheimer disease, and Huntington disease, have changes in phosphodiesterase expression in the brain.(3)PDE8B expression is higher in specific brain regions affected by ADSD (putamen, caudate nucleus, and nucleus accumbens), producing peculiar lesions in the striatum.(2,3