Similarly, a retrospective observational study of Ashkenazi Jewish patients revealed that patients with mutations in LRRK2 and GBA (described by the authors as “GBA-LRRK2-PD”) were less frequently affected by dementia, probable REM-behavior sleep disorder, and psychosis, compared to other groups (GBA-PD, LRRK2-PD, mutation-negative PD) [149]. Here, LRRK2 is linked to REM sleep behavior disorder.