Autosomal dominant striatal degeneration (ADSD) is an adult-onset movement disorder characterized by bradykinesia, dysarthria and muscle rigidity. To date, ADSD has been observed in seven individuals in one family. Onset of symptoms of ADSD is in the fourth to fifth decade of life with mild progressive dysarthria and hypokinesia. Mild bradykinesia presents predominantly as gait disturbance but also as a general slowing of movement. Dysdiadochokinesia is also present and muscle tone is slightly increased. Additional features include stiffness of the tongue and, in some patients, mild difficulties in swallowing. ADSD is characterized by dysfunction and changes of the striatal part of the basal ganglia, visible on MRI scans. It is caused by mutation in the PDE8B gene (5q13.3-q14.1) and is transmitted in an autosomal dominant manner with complete penetrance in the investigated family. Diagnosis is based on brain MRI which shows distinctive and characteristic symmetric lesions of the striatum that appear earlier than the onset of symptoms. A good correlation has been observed between clinical signs and the degree of MRI abnormalities. Differential diagnoses include other degenerative diseases causing hypokinesia (such as Parkinson's disease; see this term). However, unlike for these diseases, in ADSD, tremor is not observed. Differential diagnoses also include neuroferritinopathy (see this term). However, ADSD is characterized by hypokinesia whereas neuroferritinopathy is characterized by hyperkinesia. The characteristic MRI changes of the striatum can be regarded as pathognomonic for ADSD. Antenatal diagnosis is currently not available but is probably not necessary because of the mild course of the disease. There is currently no known treatment for ADSD and symptoms do not respond to treatment with levodopa. However, the course of the disease is mild and allows affected individuals to lead a virtually normal life. Life expectancy does not appear to be affected.
Last update: May 2010