Subtype 1: patients with mutations in the SNCA gene (gene ID: 6622) encoding α-Syn develop an autosomal dominant aggressive form of Parkinson’s with predominant protein aggregation, which is directly caused by the mutation in the SNCA gene; thus, iPSC-derived neurons from a patient with SNCA triplication (SNCA ×3) were used to model familial proteinopathy. This evidence concerns the gene SNCA and Parkinson disease.