Inclusion body myositis (IBM) is an inflammatory muscle disease characterized by slowly progressive weakness and muscle wasting. IBM affects nearly 15 million people worldwide and is the most common cause of inflammatory myopathy in people over age 50. One part of the disease mechanism is autoimmune and another part involves deposition of abnormally folded amyloid β-protein (Aβ) in the muscle cells. Experiments in mice have shown that therapy targeted against Aβ ameliorates the disease.