Tocompare for the first time the diagnostic accuracy of the immunofluorescence (IF) technique and aSyn-seed amplification assay (aSyn-SAA) of skin and cerebrospinal fluid (CSF) in disclosing pathological α-syn in idiopathic idiopathic REM sleep behavior disorder (iRBD) as early phase of a synucleinopathy. We prospectivelyrecruited41 patients with iRBD and 40 matched clinical controls including RBD associated withtype 1 Narcolepsy (RBD-NT1, 21 patients), iatrogenic causes (2 pt) or OSAS (6 pt) and 11 patients with peripheral neuropathies.IF from samples taken by skin biopsy and aSyn-SAA from skin and CSF samples were analysed blinded to the clinical diagnosis. IF showed a good diagnostic accuracy (89%) that was lower in the case of skin and CSF-basedaSyn-SAA(70% and 69% respectively) because of a lower sensitivity and specificity.However, IF showed a significant agreement with CSFaSyn-SAA. In conclusion our data may favour the use of skin biopsy andaSyn-SAAas diagnostic tools for asynucleinopathyiniRBD.
