Alpha-1 antitrypsin deficiency (AAT deficiency or AATD) is an inherited condition that increases the risk of lung and liver disease. Alpha-1 antitrypsin is a protein made in the liver that helps protect lung tissue from damage. When the amount or function of this protein is reduced, the lungs can be more vulnerable to smoke, dust, pollution and inflammation.
How AAT deficiency affects the body
AAT deficiency is caused by inherited changes in the SERPINA1 gene. Some people never develop symptoms, while others develop lung disease, liver disease or both. Lung problems often appear in adulthood and can include emphysema, COPD or bronchiectasis. Smoking can greatly accelerate lung damage.
Symptoms
Possible lung symptoms include:
- shortness of breath, especially with activity
- wheezing
- persistent cough, sometimes with mucus
- repeated respiratory infections
- reduced exercise tolerance
- fatigue or unexplained weight loss
Liver involvement can cause jaundice, dark urine, abdominal swelling or swelling of the legs. Rarely, AAT deficiency can cause painful inflammatory skin lesions.
Who should consider testing?
A healthcare professional may recommend testing when COPD or emphysema occurs at a younger age, when lung disease develops without typical smoking or occupational exposure, when there is unexplained liver disease, or when a close relative has AAT deficiency. People diagnosed with COPD can also discuss AAT testing with their healthcare professional.
Diagnosis
A blood test can measure the amount of alpha-1 antitrypsin in the blood. If the level is low or the clinical picture suggests AAT deficiency, additional phenotype or genetic testing can help confirm the diagnosis and identify the underlying variant. Lung function testing may be used to assess airflow limitation, and liver tests or imaging may be needed when liver disease is suspected.
Because the condition is inherited, genetic counseling can help individuals and families understand test results and what they may mean for relatives.
Treatment
There is currently no cure for AAT deficiency, but treatment can reduce complications and slow lung damage. People with lung disease may receive standard COPD treatments such as bronchodilator inhalers, pulmonary rehabilitation, vaccinations and oxygen therapy when medically indicated.
Intravenous AAT augmentation therapy may be considered for selected people with AAT deficiency and emphysema. It raises circulating AAT levels and is intended to slow further lung damage. It does not treat liver disease and is not appropriate for everyone, so specialist assessment is required.
Severe lung or liver disease may occasionally require transplantation.
Protecting the lungs and liver
- Do not smoke, and avoid secondhand smoke.
- Reduce exposure to dust, fumes and air pollution when possible.
- Follow recommended respiratory vaccination guidance.
- Discuss alcohol use, medicines and supplements with a healthcare professional if liver disease is present.
- Attend regular follow-up for lung and liver health when advised.
When to seek urgent help
Seek emergency medical care for severe or rapidly worsening breathing difficulty, blue or gray lips or skin, confusion, collapse, severe chest pain, or coughing up a significant amount of blood. Seek prompt medical assessment for jaundice, marked abdominal swelling, vomiting blood, black stools or a sudden worsening of known liver disease.
Related topics
Sources
- National Heart, Lung, and Blood Institute: Alpha-1 Antitrypsin Deficiency
- MedlinePlus: Alpha-1 Antitrypsin Deficiency
- MedlinePlus: Alpha-1 Antitrypsin Testing
Last reviewed: 4 September 2026. This page provides general health information and does not replace individual medical advice.