LRRK2 and irritable bowel syndrome: Genetic evidence has suggested that LRRK2 is a link between IBD and PD (Umeno et al., 2011; Zhu et al., 2019), and mild intestinal inflammation is common in patients with PD (Forsyth et al., 2011); therefore, it is reasonable to speculate that the colonic LRRK2 expression would be increased in those who are in the body-first subtype of PD.