alpha-Dystroglycan is an extracellular adhesion protein that is known to interact with different ligands. The interaction is thought to stabilize the integrity of the plasma membrane. The N-terminal part of alpha-dystroglycan may be proteolytically processed to generate a small 38 kDa protein (alpha-DG-N). The physiological significance of alpha-DG-N is unclear but has been suggested to be involved in nerve regeneration and myelination and to function as a potential biomarker for neurodegenerative and neuromuscular diseases. In this report we show that alpha-DG-N is released into different body fluids, such as lachrimal fluid, cerebrospinal fluid (CSF), urine and plasma. To investigate the significance of alpha-DG-N in CSF we examined the levels of alpha-DG-N and known neurodegenerative markers in CSF from patients diagnosed with Lyme neuroborreliosis (LNB) and healthy controls. In untreated acute phase LNB patients, 67% showed a significant increase of CSF alpha-DG-N compared to healthy controls. After treatment with antibiotics the CSF alpha-DG-N levels were normalized in the LNB patients. (C) 2011 Elsevier Inc. All rights reserved.