LRRK2 and Parkinson disease: Other genes found in human genetic studies linked to PD include: Parkin (PRKN), a ubiquitin ligase associated with the ubiquitin-proteosome system; DJ-1, a poorly characterized anti-oxidant protein; LRRK2, a putative protein serine threonine kinase; and PINK1, a putative PTEN induced protein kinase.