SNCA and Parkinson disease: According to a recent study by Chu et al. [113], nigrostriatal degeneration (progressive loss of neurons in a specific brain pathway called the nigrostriatal pathway that is critical for movement control) can happen without alpha-synuclein pathology, according to the results from a cohort of people with modest motor impairments, a prodromal stage that does not fully fit the criteria for PD.