Similarly, PET studies in SCA2 and SCA3 have reported signs of presynaptic denervation with a reduction in striatal dopamine transporter levels and preservation of postsynaptic striatal D2 receptors, resembling the pattern of idiopathic Parkinson's disease (PD) [13, 14, 15]. The gene discussed is SLC6A3; the disease is spinocerebellar ataxia type 2.