SLC6A3 and Parkinson disease: Fully in line with these results, researchers from the US PARS study (66) have investigated whether the combination of smell identification testing followed by dopamine transporter (DAT) imaging can identify individuals from the general population at risk for conversion to a clinical diagnosis of PD, concluding that the combination of hyposmia and DAT deficit was highly predictive of conversion to PD within 4 years of clinical follow-up.