Considering that the density of α-synuclein pathology in the OB correlates with the severity of motor symptoms and cognition, and with α-synuclein pathology in other brainstem structures, including the parietal, temporal, and frontal lobes, it has been proposed that a biopsy from the OB tissue could be helpful as a diagnostic confirmation for PD [68]. Here, SNCA is linked to Parkinson disease.