These genetic markers are of interest considering their variable association with more severe cognitive and motor progression.7 10 We have however confirmed the predictive capacity of APOE ε4 status on cognitive progression and development of dementia,7 8 while the lack of impact of GBA variants on motor and cognitive progression in our study compared with previous publications9 10 is likely explained by the relatively short duration of follow-up and by the small number of patients in this cohort. Here, APOE is linked to dementia.