Alpha 1 Antitrypsin Deficiency
About Alpha 1 Antitrypsin Deficiency (AAT)
Alpha 1 antitrypsin deficiency is an inherited genetic disorder that can cause liver or lung disease. Alpha 1 antitrypsin is a protein that is made in the liver and is responsible for protecting organs from the harmful effects of other proteins in the body.
Alpha 1 antitrypsin deficiency occurs if the AAT proteins are produced in the wrong shape and are unable to enter the bloodstream because they are trapped in liver cells.
Why it is Problematic
In AAT deficiency, too few AAT proteins reach the lungs to protect them, which increases the risk of developing lung disease. Likewise, because excess AAT proteins remain in the liver, the risk of developing liver disease also increases.
Severe AAT deficiency occurs when blood levels of AAT fall below the minimum amount required for adequate lung protection. Severe AAT deficiency dramatically increases the risks for developing liver disease or lung disease.
Causes and Risk Factors
AAT deficiency is caused by mutations in the SERPINA1 gene, which provides the body instructions as to how to produce the alpha-1 antitrypsin protein. Two copies of the mutation (homozygous), one copy from each parent must be inherited for an individual to have AAT deficiency. Individuals with one copy of the mutation (heterozygous) may have slightly impaired AAT production, but usually will not experience any problems.
Environmental factors can impact the severity of AAT deficiency. Exposure to smoke, dust, and chemical fumes can all increase the symptoms of AAT deficiency.
AAT deficiency symptoms reflect as the symptoms of liver disease or lung disease. AAT deficiency can affect individuals of all ages, including infants, but symptoms are most likely to occur between the ages of 20 and 50 and include:
- Shortness of breath after even mild activity
- Unintentional or unexplained weight loss
- Respiratory infections
- Rapid heartbeat upon standing
- A barrel-shaped chest
- Hacking cough
Cirrhosis and liver disease usually occur in infancy and early childhood and 15% of adults with AAT deficiency develop cirrhosis.
In order to diagnose AAT deficiency, a doctor performs a physical examination to look for a barrel chest or listens to the lungs for wheezing.
Tests to determine the diagnosis of AAT deficiency may include:
- Alpha 1 antitrypsin blood test
- Arterial blood gases test
- Chest X-ray
- CT scan
- Genetic testing
- Lung function test
AAT deficiency may be suspected if the patient was diagnosed with emphysema prior to the age of 45 and never smoked, was exposed to toxins, or has a family history of AAT deficiency. A patient with liver disease or hepatitis without other causes or family history of liver problems may also be suspected of having AAT deficiency.
Treatment and Prevention
Treatment will strive to replace the missing AAT protein by injecting it through a vein once a week. Anyone who suffers from an AAT deficiency and smokes must quit.
Treatment for any other simultaneous condition, including emphysema and cirrhosis, will coincide with treatment for Alpha 1 antitrypsin deficiency.
Many of those with AAT deficiency are unaware that they have the condition, making the exact incidence unknown. It is believed that 1 in 1,500- 3,500 people of European ancestry have AAT deficiency. The condition is uncommon in those of Asian ancestry. Approximately 100,000 Americans suffer from AAT deficiency. Approximately 3% of patients with an AAT deficiency who have a related lung or liver disease die each year.