PRKN and Parkinson disease: Parkinsonism associated with Parkin gene mutation was one of the most common familial forms of PD, which was characterized by early onset of symptoms (mainly before age 50), slow progression, elective dopaminergic neuronal loss and the absence of Lewy bodies (Gouider‐Khouja et al., 2003; Lucking et al., 2000; Mizuno, Hattori, & Matsumine, 1998).