PRKN and Parkinson disease: Olfactory dysfunction occurs in a range of neurodegenerative diseases, including PD at motor presentation (Silveira‐Moriyama et al., 2009), prodromal PD (Barber et al., 2017; Campabadal et al., 2019; Lo et al., 2021; Noyce et al., 2014; Siderowf et al., 2012), progressive supranuclear palsy (Silveira‐Moriyama et al., 2010), and Alzheimer's disease (Jung et al., 2019), but olfaction is generally normal in multiple system atrophy (Xia & Postuma, 2020) and Parkin‐related PD (Malek et al., 2016).