In recent decades, several biomarkers in the body fluid, such as orexin, 8-Hydroxy-2′-Deoxyguanosine, peripheral proteasomes, caspases, dopamine, dopamine receptor, alpha-synuclein, and apolipoprotein A1 (ApoA1), have been suggested to be diagnostic of PD [11]; however, some of these biomarkers fail to reflect the disease course while others only exhibit vague results. Here, APOA1 is linked to Parkinson disease.