Around a quarter (24.6%) of sporadic PD cases carry the common LRRK2 risk variant rs10878226, which is associated with PD (combined odds ratio 1.20, 95% CI 1.08–1.33, p = 6.3 × 10−4, n = 6129) (Mata et al., 2012). Here, LRRK2 is linked to Parkinson disease.