Alpha-1 antitrypsin is a protein in the blood that protects the lungs from damage caused by activated enzymes.
Alpha-1 antitryps helps to inactivate several enzymes, the most important of which is elastase.
What is elastase?
Elastase is an enzyme produced by white blood cells called neutrophils and is part of the body's normal response to injury and inflammation. Elastase breaks down proteins so that they can be removed and recycled by the body. If its action is not regulated by Alpha-1 antitrypsin, elastase will also begin to break down and damage lung tissue.
Inherited genes that code for Alpha-1 antitrypsin:
Each individual inherits two copies of the gene that codes for Alpha-1 antitrypsin. It is called the protease inhibitor (SERPINA1) gene. This gene is co-dominant, which means that each SERPINA1 gene copy is responsible for producing half of the body's Alpha-1 antitrypsin. If there is a change or mutation in one or both of the gene copies, then less Alpha-1 antitrypsin and/or Alpha-1 antitrypsin with reduced function is produced.
Low Alpha-1 antitrypsin production:
When Alpha-1 antitrypsin production drops below 30% of normal, the affected person will experience a disorder called alpha-1 antitrypsin deficiency. People with this disorder are at a considerable risk of developing emphysema, a progressive lung disease, in early adulthood. If they smoke or are exposed to occupational dust or fumes, the lung damage tends to occur sooner and be more severe.
Certain types of dysfunctional Alpha-1 antitrypsin accumulate in the liver cells, where it is produced. As Alpha-1 antitrypsin builds up in these cells, it forms abnormal protein chains and begins to destroy the cells and damage the liver. About 10% of newborns with Alpha-1 antitrypsin deficiency have liver damage and are jaundiced. In severe cases, these infants may require a liver transplant to survive. Alpha-1 antitrypsin deficiency is currently the most common genetic cause of liver disease in the pediatric population.
Increased risk for chronic liver disease:
In adults with Alpha-1 antitrypsin deficiency, the risk of developing chronic liver disease, cirrhosis, and liver cancer (hepatocellular carcinoma) is increased. Few adults with Alpha-1 antitrypsin deficiency actually have signs or symptoms of liver disease, however. The amount and function of the Alpha-1 antitrypsin depends on the gene mutation that is inherited. While there are more than 120 different alleles in the SERPINA1 gene, only a few are common. Most people in the U.S., about 90%, have two copies of the normal "wild type" M gene (MM). The most common abnormal genes are labeled S and Z.
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