PRKN and Parkinson disease: The characteristics of EOPD caused by mutations in PARK2 include typical clinical symptoms of PD, such as bradykinesia, rigidity, and resting tremor, and other features, such as an early onset at an age <40 years, a slower disease progression, a marked and sustained response to levodopa, levodopa‐induced motor fluctuations, dyskinesias, foot dystonia, hyperreflexia of the lower extremities, symptoms of diurnal fluctuations with sleep benefits, and psychiatric symptoms (Grunewald, Kasten, Ziegler, & Klein, 2013; Khan et al., 2003; Schrag & Schott, 2006).