LRRK2 and Parkinson disease: C. elegans expresses various human gene homologues of LRRK2 (lrk-1), PINK1 (pink-1), Parkin (pdr-1), and DJ-1 (dnaj-1.1 and dnaj-1.2) that are directly implicated in familial forms of human PD but do not express α-Synuclein [21].