SNCA and Parkinson disease: Since the first PD-associated substitution mutation of alanine in position 53 for threonine (A53T) in α-synuclein was identified more than 20 years ago (Polymeropoulos et al., 1997), many other genes with Mendelian inheritance have been identified, and the number of PD-related genes as risk factors has exponentially increased (Brás and Outeiro, 2021; Oliveira et al., 2021).