SNCA and Parkinson disease: Cerebrospinal fluid (CSF) levels of alpha‐synuclein oligomers longitudinally increase in PD compared to aged‐matched controls.17, 18, 19 Additionally, the ratio of oligomeric to total alpha‐synuclein also increases in the CSF of PD patients when compared to control and this increased ratio has been associated with motor decline.20, 21 Homovanillic acid (HVA) and 3,4‐Dihydroxyphenylacetic Acid (DOPAC) are two primary metabolites of DA and can be used as a CSF marker of DA metabolism.