Detection of TDP‐43 seeding activity in the olfactory mucosa from patients with frontotemporal dementia

INTRODUCTIONWe assessed TAR DNA‐binding protein 43 (TDP‐43) seeding activity and aggregates detection in olfactory mucosa of patients with frontotemporal lobar degeneration with TDP‐43‐immunoreactive pathology (FTLD‐TDP) by TDP‐43 seeding amplification assay (TDP43‐SAA) and immunocytochemical analysis.METHODSThe TDP43‐SAA was optimized using frontal cortex samples from 16 post mortem cases with FTLD‐TDP, FTLD with tau inclusions, and controls. Subsequently, olfactory mucosa samples were collected from 17 patients with FTLD‐TDP, 15 healthy controls, and three patients carrying MAPT variants.RESULTSTDP43‐SAA discriminated with 100% accuracy post mortem cases presenting or lacking TDP‐43 neuropathology. TDP‐43 seeding activity was detectable in the olfactory mucosa, and 82.4% of patients with FTLD‐TDP tested positive, whereas 86.7% of controls tested negative (P MAPT mutations tested negative. In TDP43‐SAA positive samples, cytoplasmatic deposits of phosphorylated TDP‐43 in the olfactory neural cells were detected.DISCUSSIONTDP‐43 aggregates can be detectable in olfactory mucosa, suggesting that TDP43‐SAA might be useful for identifying and monitoring FTLD‐TDP in living patients.