Studies with PD patient-derived mutant ATP13A2 fibroblasts and ATP13A2-knockdown DA neurons have shown that PD-linked mutations in ATP13A2 lead to several lysosomal alterations, including impaired lysosomal acidification, decreased activity of lysosomal enzymes, reduced degradation of lysosomal substrates and defective clearance of autophagosomes (125). This evidence concerns the gene ATP13A2 and Parkinson disease.