These individuals are more likely to experience a delay in diagnosis and higher rates of misdiagnosis.9 To study this prodromal phase, we have recruited first‐degree relatives of PD subjects, unselected on the basis of genotype (e.g., presence of leucine‐rich repeat kinase 2 [LRRK2] or glucocerebrosidase [GBA] mutations), given that this group have an increased risk of developing PD compared to those without affected relatives.10 This evidence concerns the gene LRRK2 and Parkinson disease.