LRRK2 and Parkinson disease: Leucine-rich repeat kinase 2 (LRRK2) was originally defined by linkage analysis of familial Parkinson’s disease (PD), and its association with inflammatory bowel disease (IBD) and leprosy has been demonstrated recently (Funayama et al., 2002; Paisán-Ruíz et al., 2004; Barrett et al., 2008; Zhang et al., 2009).