However, the most compelling evidence for a central involvement of mitochondria in PD pathogenesis was provided by what we learned in the past decade about the functions of the proteins encoded by two genes mutated in autosomal recessive forms of PD: the RING/HECT hybrid E3 ubiquitin ligase Parkin and the mitochondrial serine/threonine kinase PINK1. The gene discussed is PINK1; the disease is Parkinson disease.