It is not necessary, as in several monogenic (LRRK2, PRKN, and PINK1) and sporadic PD α-syn deposition is not detected in CSF-aS-SAA nor neuropathological findings, despite the presence of nigrostriatal dopaminergic dysfunction [3, 4, 23], which might be mediated by other pathological mechanisms [24]. The gene discussed is LRRK2; the disease is Parkinson disease.