Many studies have been conducted by dosing these proteins in CSF, regarded as the biological fluid that better recapitulates central nervous system (CNS) pathologies, showing that o-α-synuclein is a promising biomarker to distinguish PD patients from HCs, while results for p-tau181 are more conflicting [13,14,15,16,17,22,23,24,25]. The gene discussed is SNCA; the disease is Parkinson disease.