Mutations in the LRRK2 gene are the common cause of PD (Paisan-Ruiz et al., 2004; Zimprich et al., 2004). LRRK2 is a 286 kDa large, multi-domain protein. It contains both protein kinase and a GTPase. LRRK2 also contains the member of the receptor interacting protein kinase (RIPK) family. Majority of the pathogenic mutations in LRRK2 lie in its catalytic domains. At least 40 mutations identified in LRRK2 gene is found to be associated with the most common familial forms of PD, some sporadic forms of PD, and with typical idiopathic late-onset PD (8-12). Collectively these LRRK2 mutations account for the majority of autosomal-dominantly inherited PD (Kett and Dauer, 2012). LRRK2-associated PD is largely indistinguishable from sporadic PD both…show more content… However, mutations in the GTP-binding domain reduce the rate of GTP hydrolysis in wild-type LRRK2, suggesting that these mutations may not affect kinase activity (Lewis et al., 2007; Li et al., 2007). LRRK2 mutations in PD show enhanced toxicity that results in significantly increased cell death than the wild-type protein in cell lines and primary neurons. Most of the PD mutations appear to cause cell death by altering the features of LRRK2 biology but that nonetheless requires intact (basal) kinase function. LRRK2 is a signaling molecule and that kinase activity is one key part of the signaling process. LRRK2 becomes pathogenic when the kinase is hyperactive or misregulated, and this may involve signaling pathways. Some recent evidence suggests that LRRK2 or homologs in other species have roles in neurite outgrowth and sorting of molecules along axons (MacLeod et al., 2006; Sakaguchi-Nakashima et al., 2007). Therefore, LRRK2 probably has activities that are important (perhaps even required) for normal neuronal…show more content… Mutations are found throughout the protein, although missense mutations are commonly found in the kinase region. Both truncating and destabilizing mutations are also found, which support the idea that pathogenic mutations cause disease through a loss of function. In addition, PINK1 overexpression protects against oxidative and apoptotic stressors in a kinase dependent manner (Petit et al., 2005). Thus, PINK1 loss of function appears to promote PD related