Each disorder is characterized by the aggregation of specific proteins: examples are beta-amyloid and TAU in Alzheimer's disease (27), NACP/α-synuclein in Parkinson's disease (28), huntingtin in Huntington's disease (29), TDP-43 in amyotrophic lateral sclerosis and frontotemporal lobar degeneration (30). This evidence concerns the gene SNCA and early-onset autosomal dominant Alzheimer disease.