A typical feature of the brain in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is the deposition of the protein TDP-43. TDP-43 is deposited years before the onset of disease symptoms. However, so far the disease-typical marker TDP-43 cannot be measured in the blood or cerebrospinal fluid of patients, which often leads to a delay in diagnosing the disease and the development of disease-specific therapies. In this project, I will use cerebrospinal fluid samples of patients with TDP-43 specific diseases and use mass spectrometry to identify markers that indicate the development of TDP-43 pathology in order to identify patients during an early disease stage.