Assays to detect abnormal alpha-synuclein in the skin and CSF are already commercially available in some regions.74 There is evidence for the accuracy of CSF seeding assays in differentiating MCI-LB from controls and MCI-AD.70 We are unaware of evidence for the detection of alpha-synuclein in skin in MCI-LB, but there is evidence that skin alpha-synuclein can differentiate idiopathic RBD from controls.75 Here, SNCA is linked to Alzheimer disease.