LRRK2 and Parkinson disease: PD patients carrying the LRRK2 G2019S variant [20, 21, 30, 31] had lower RBDSQ scores than those without LRRK2 G2019S (SMD, − 0.33; 95% CI, − 0.47 to − 0.20; I2 = 0.0%) (Fig. 5c), while there was no difference in RBDSQ score between patients with and without LRRK2 G2385R [28, 35] (Fig. 5d).