A minority (≈5%) of middle-aged and elderly patients with GD1 develop Parkinson’s Disease (PD) and dementia with Lewy bodies (DLB) [29–31] but the frequency is greatly increased over the healthy population control subject has also been shown that GCase activity is decreased in normal ageing and in the substantia nigra and putamen of patients with PD together with characteristic deposits of phosphylated alpha-synuclein [32, 33]. This evidence concerns the gene SNCA and Parkinson disease.