Elevated levels of a C-terminal agrin fragment identifies a new subset of sarcopenia patients

► First report on CAF, a neurotrypsin proteolysis product of agrin. ► Agrin proteolysis (CAF) is detectable in humans and elevated in sarcopenia patients. ► This report links elevated proteolysis of the neuromuscular junction to sarcopenia. ► Selective inhibition of neurotrypsin lowers agrin degradation.