Alpha 1-Antitrypsin Deficiency (AAT)

Alpha 1-antitrypsin (AAT) deficiency is a rarely diagnosed genetic disease that affects the liver and lungs. AAT is a protease inhibitor synthesized primarily by hepatocytes. The role of AAT is to protect tissue from the inflammatory effects of neutrophil elastase (NE). NE is an enzyme that degrades elastin, basement membrane and other matrix components.

The deficiency occurs because the AAT produced is abnormal which results in AAT entrapment within the hepatocyte rough endoplasmic reticulum. As much as 85% of AAT produced can be trapped in the hepatocyte forming periodic acid Schiff-positive inclusions that are associated with liver disease.

When a hepatic inflammatory condition occurs in an AAT deficient patient, NE cannot be adequately counteracted resulting in abnormal collagen deposition and cirrhosis. AAT associated liver disease is more prevalent in children but may be exacerbated in adults by external liver insults.

Treatment options include AAT augmentation by IV infusion for lung disease. Lung or liver transplants are reserved for end-stage disease resistant to conservative treatment. Liver transplantation replaces abnormal liver cells with donor tissue that produces normal AAT. Gene therapy is also being studied as a form of treatment.


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