Alpha1-antitrypsin (A1AT) deficiency is an inherited disorder that may lead to lung and/or liver disease.
A1AT is a protein made by cells in the liver and passed into the bloodstream. Its job is to protect organs including the lungs from damage by other proteins called protease enzymes. In A1AT deficiency, the levels of A1AT are reduced, or the A1AT produced is abnormal, which may result in protease enzymes causing damage to normal tissue. If the alveoli (small air sacs of the lung) become damaged, the disease emphysema may develop.
About one in every 2500 people in Australia inherit a genetic disorder that results in A1AT deficiency, however, it is estimated that a significant number of people are unaware that they have the disorder. It is most common among people of Northern European or Iberian (Spanish peninsula) descent.
A1AT is an inherited condition caused by an abnormality of the A1AT gene.
Not everyone who inherits an abnormal gene will develop disease. Whether a person develops symptoms or not will depend upon the alleles (variations of the gene) 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.
A1AT deficiency can lead to the development of emphysema, a form of chronic obstructive pulmonary disease (COPD) in adults. The most common symptom of emphysema is shortness of breath, which usually gets worse over time. People who show signs of developing emphysema at a young age (30-45 years) may have A1AT deficiency.
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 your doctor may request include liver function tests, lung function tests, imaging of the lungs and/or liver, and genetic testing.
Medical care of people with A1AT deficiency and lung disease includes treatment for emphysema, such as bronchodilators and other medicines to help with breathlessness, influenza and pneumococcal vaccination and, if necessary, antibiotics for chest infections. The most important thing people with A1AT deficiency can do to help themselves is to stop smoking.
There is a specific therapy for emphysema due to A1AT deficiency which is called A1AT augmentation, or replacement, therapy and is given by intravenous infusion. However, it is not yet available in Australia. A Cochranew review found there was little difference in a patient's quality of life or whether their disease worsened whether or not they had A1AT replacement therapy. (The Cochrane Collaboration is an international organisation which reviews evidence for medical interventions in order to help people make informed decisions about their health).
In severe cases of lung or liver disease with A1AT deficiency, organ transplantation may be considered.
Last Reviewed: 26 November 2012