Fairfoul et al. (2016); Shahnawaz et al. (2017); Shahnawaz et al. (2020); Groveman et al. (2018); Garrido et al. (2019); Kang et al. (2019); Manne et al. (2019); van Rumund et al. (2019); Rossi et al. (2020); and Bargar et al. (2021b) Lower sensitivity (40%–78%) in LRRK2-associated PD, possibly due to non-α-synuclein pathologies underlying this syndrome and not useful in autosomal recessive forms of PD associated with α-synuclein-negative nigral degeneration (Garrido et al., 2019; Brockmann et al., 2021). Here, SNCA is linked to Parkinson disease.