LRRK2 and Parkinson disease: An analysis of PD cases according to age at onset (≤ 50 years vs. >50 years) showed that LRRK2 mutations were more frequent among late-onset PD cases (61/636, 9.6%; 95% CI [7.4–12.2] vs. 71/1063, 6.7%; 95% CI [5.3–8.4], Fisher's exact test: OR 1.5, 95% CI [1.0–2.1], p = 0.03; Table 2).