PINK1 and Parkinson disease: In humans, motor symptoms manifest as tremors, slowness of movement (bradykinesia), muscle rigidity, and altered gait and balance.3-5 The molecular mechanisms underlying the death of the dopaminergic neurons in PD remain poorly understood.1,6,7 Although the majority of PD cases (>85%) are idiopathic in nature with no known cause, familial forms of the disease are thought to be strongly linked to inheritance of mutations within one of many PD-associated causative genes including PINK1. 8 Inheritance of biallelic PINK1 mutations is associated with early-onset PD.8,9