In particular, a number of genes have been found to have a causal role in familial forms of PD, including α-synuclein, Leucine-rich repeat kinase 2 (LRRK2), parkin and PTEN-induced putative kinase 1 (PINK1) (for review see Hernandez et al., 2016). Here, LRRK2 is linked to Parkinson disease.