Parkinsons disease (PD) is the second most common neurodegenerative disease characterized by the selective loss of dopaminergic neurons in the substantia nigra.Genetic studies have identified a number of genes associated with familial forms of PD,including a-synuclein,parkin,UCH-L1,PINK1,DJ-1,and LRRK2.Although familial PD accounts for less than 10% of PD cases,studies of the identified familial PD gene products have provided invaluable insights into the etiology and pathogenesis of PD.PINK1 is a novel,581-amino-acid protein of unknown function initially isolated in a screen for potential mediators of the tumor-suppressive activity of PTEN.Recently,homozygons mutations in PINK1 were identified as a common cause for autosomal recessive,early-onset PD.