When it comes to screening efforts for typical PD, more invasive and expensive tests, e.g., the α-synuclein seeding amplification assay from cerebrospinal fluid (CSF) or skin biopsies, or the administration of a dopamine transporter scan, could be employed as additional steps to increase diagnostic accuracy, such as when aiming to enroll subjects with probable PD into specific, disease-modifying trials25–29. This evidence concerns the gene SLC6A3 and Parkinson disease.