PINK1 and Parkinson disease: Over the past several years, studies of the PTEN-induced putative kinase 1 (PINK1) and parkin genes, loss-of-function mutations of which give rise to heritable forms of Parkinson's disease [7], [8], have demonstrated that these genes encode components of a mitochondrial quality control system that promotes the selective degradation of defective mitochondria [9], [10], [11].