Autosomal dominant familial Parkinson's disease (PD) due to the alpha-synuclein (G209A) mutation shares similar clinical characteristics with sporadic PD. Pathological studies however indicate more widespread neuronal degeneration in the familial form. We performed (123)I-FP-CIT SPET (DaTSCAN) study in nine patients with familial PD carrying the alpha-synuclein (G209A) mutation and fifteen matched patients with sporadic disease. Both groups had equal radioligand reduction uptake in the striatum but the alpha-synuclein patients showed less asymmetry and increased putamen to caudate ratio. Our findings indicate that there are minor differences in DAT SPET parameters between alpha-synuclein and sporadic PD patients insufficient to provide differential diagnosis.