SLC6A3 and Parkinson disease: Fullard et al., using the PARS cohort of 198 asymptomatic individuals, found that those at high risk for PD had slightly higher vitamin D levels (27.8 ng/mL vs. 24.7 ng/mL, p = 0.09), and no association with dopamine transporter binding, suggesting that VitD insufficiency is not a preclinical marker [213].