Serpin A3 belongs to the Serpin superfamily of serine protease inhibitors. Serpin A3 has been shown to inhibit some serine proteases, such as neutrophil cathepsin G and mast cell chymase. Serpin A3 is synthesized initially in the liver and secreted in plasma. Serpin A3 has been found in the amyloid plaques from the hippocampus of Alzheimer disease brains. In addition to, Serpin A3 is associated with liver disease and Parkinson disease and chronic obstructive pulmonary disease.