Alpha-1 Antitrypsin (AAT) is a 52 kDa glycoprotein that is principally synthesized by the liver. It is the archetype of the serine
protease inhibitor (Serpin) superfamily of proteins, which has a major role in inactivating neutrophil elastase and other proteases to
retain protease–antiprotease equilibrium. AAT deficiency is a rare monogenic disorder characterized by low levels of AAT in serum and
the lungs and it is well known to be associated with emphysema and liver disease. Inadequate knowledge of AAT deficiency might be
due to under-recognition of this protein. To date, the exact role of AAT deficiency in various diseases has not been extensively elucidated.
In this review, the current knowledge regarding the role AAT in various disorders will be discussed.