The Skin as a Window to the Central Nervous System in Frontotempolar Lombar Degeneration

Frontotemporal lobar degeneration (FTLD) is a clinically heterogeneous syndrome, characterized by progressive decline in behaviour and/or language. From a pathological standpoint, like the great majority of neurodegenerative disorders, FTLD are proteinopathies, which are characterized by the presence of specific protein deposits in the Central Nervous System (CNS). Accordingly, the two main deposits observed in FTLD are either made of Tau or transactive response DNA binding protein 43 (TDP-43). In pathological conditions such as FTLD, both proteins are aggregated and hyperphosphorylated. It is now well established that the pathological process in some proteinopathies such as synucleinopathies (of which Parkinson's disease is the main representative) is not limited to the brain but also widespread throughout the peripheral autonomic networks, including the autonomic innervation of the skin. In this context, many independent studies have shown that the pathological process in PD could be detected using routine punch skin biopsies opening the way for the development of original histopathological markers of the disease. Our hypothesis is that such a scenario could also occur in FTLDs and that the detection of the pathological tau or TDP-43 protein in the skin could help in diagnosing FTLD. This is especially relevant as, despite the recent progress in genetics, neurobiology and neuroimaging, there are no available biomarkers for FTLD.