OBJECTIVE: To describe the clinical and neuroradiologic features and chromosomal mapping of a novel autosomal dominant disease affecting the basal ganglia. METHODS: The authors characterized a large family with autosomal dominant basal ganglia disease (ADSD) clinically and by MRI, MR spectroscopy (MRS), and SPECT. The authors performed a whole genome genetic linkage scan to map the underlying genetic defect. RESULTS: The main clinical features of the disease are dysarthria and gait disturbance without any apparent reduction in life expectancy. MRI demonstrated a distinctive lesion pattern restricted mainly to the putamen and caudate nucleus. Genetic linkage analysis localized the causative genetic defect to a 3.25 megabase candidate region on chromosome 5q13.3-q14.1. CONCLUSIONS: ADSD is an autosomal dominant basal ganglia disease mapping to chromosome 5q13.3-q14.1.