Alpha1-antitrypsin deficiency
Alpha1-antitrypsin (A1AT) deficiency is an inherited disorder that may lead to lung and/or liver disease.
A1AT is a protein that protects the body against damage by protease enzymes. In A1AT deficiency, the levels of A1AT are reduced, or the A1AT produced is abnormal. This lack of A1AT or abnormal A1AT can result in protease enzymes causing damage to normal tissue.
About one in every 2500 people in Australia has severe A1AT deficiency (A1AT levels less than 20 per cent of normal). However, it is estimated that a significant number of people are unaware that they have the disorder.
What causes alpha1-antitrypsin deficiency?
A1AT is an inherited condition caused by an abnormality of the A1AT gene. There are several different forms (alleles) of the A1AT gene, including both abnormal and normal forms.
Fortunately, not everyone who inherits an abnormal gene will develop disease. Whether a person develops symptoms or not will depend upon what alleles they have inherited and the levels of A1AT in their blood. It is usually only when the A1AT levels are less than 30 per cent of normal that lung disease develops. Smoking greatly increases the risk of developing lung disease in people with A1AT deficiency.
Symptoms and diagnosis of alpha1-antitrypsin deficiency
A1AT deficiency can lead to the development of emphysema, a form of chronic obstructive pulmonary disease in adults. The most common symptom of emphysema is shortness of breath, which usually gets worse over time.
A1AT deficiency can result in liver disease in both children and adults. Symptoms of liver disease may include jaundice (yellowing of the skin and eyes), swelling of the abdomen and poor appetite.
A1AT deficiency is diagnosed by testing the levels of A1AT in the blood. Other tests may include liver function tests, lung function tests, imaging of the lungs and/or liver, and genetic testing.
What treatment is available for alpha1-antitrypsin deficiency?
Treatment of people with A1AT deficiency and lung disease includes the normal treatment for emphysema, such as bronchodilators and other medicines to help with breathlessness, and antibiotics for chest infections. The most important thing people with A1AT deficiency can do to help themselves is to stop smoking.
Specific therapy for emphysema due to A1AT deficiency may include A1AT replacement therapy. However, this therapy has not been conclusively shown to halt the decline in lung function.
In severe cases of lung or liver disease, organ transplantation may be considered.
Last Reviewed: 02 November 2007
