Protein aggregation in the brain is central to neurodegenerative diseases, with α-synuclein (SYN) and Tubulin Polymerization Promoting Protein/p25 (TPPP) aggregation being characteristic of Parkinson’s disease and multiple system atrophy15–17, and β-amyloid and tau aggregation being characteristic of Alzheimer’s disease18,19. The gene discussed is TPPP; the disease is Parkinson disease.