Most PD-related gene products are found in mitochondria [27]–[29] and overexpression, deletion or mutation of several familial PD-related gene products (α-synuclein, parkin, PINK1, and LRRK2) affect mitochondrial function, integrity, and susceptibility to mitochondrial toxins [30]–[33]. Here, LRRK2 is linked to Parkinson disease.