The number of SNCA alleles is dose-dependently linked to Lewy body disease severity, with cases of duplication causing milder forms of late-onset PD, whereas triplications cause severe clinical manifestations, with parkinsonism, autonomic dysfunction, dementia and, in some cases, vacuolation of cortical tissue [71, 107, 170, 203, 227]. This evidence concerns the gene SNCA and Parkinson disease.