MARK2 and Parkinson disease: Loss-of-function mutations in the gene encoding PTEN-induced kinase 1 (PINK1) are causally linked to a recessively inherited form of Parkinson’s disease (PD) clinically similar to idiopathic PD with earlier onset.1 The normal function of PINK1 and the mechanisms by which PINK1 mutations cause PD remain areas of active research.2 The primary sequence of PINK1 contains a mitochondrial targeting sequence at the N-terminus and a kinase domain homologous to serine/threonine kinases of the calcium/calmodulin family.