In fact, regardless of the mutational status of LRRK2 gene in PD patients with or without LB pathology, ~20–100% of α-synuclein-positive LB also contained high levels of LRRK2 mRNA (Daher et al., 2014), which suggests that LRRK2 and α-synuclein have synergetic effects (Guerreiro et al., 2013). Here, SNCA is linked to Parkinson disease.