Alpha-1 antitrypsin (AAT) is a liver-made serine protease inhibitor that protects tissues—especially lung alveoli—by neutralizing enzymes like neutrophil elastase released during inflammation. It limits tissue damage, regulates inflammation, and helps maintain normal lung structure. AAT deficiency allows unchecked elastase activity, causing emphysema, and can lead to liver disease from misfolded AAT accumulation.

Alpha-1 antitrypsin (AAT) deficiency causes lung and liver symptoms: breathlessness, wheeze, chronic cough, recurrent chest infections, reduced exercise tolerance and early-onset emphysema or COPD. Liver signs include jaundice, fatigue, abdominal swelling, hepatomegaly, elevated liver enzymes, cirrhosis and portal hypertension; newborns may have prolonged neonatal jaundice. Less commonly, panniculitis and vasculitis can occur.

Alpha-1 antitrypsin (AAT) is a protective protein that travels from the liver to the lungs, where it neutralizes neutrophil elastase and other proteases. By inhibiting these enzymes, AAT prevents destruction of alveolar walls and preserves lung elasticity, reducing inflammation and the risk of emphysema and COPD. AAT deficiency permits unchecked protease activity, leading to progressive lung tissue damage.

Alpha-1 antitrypsin deficiency is not typically autosomal dominant. It follows a codominant pattern: different SERPINA1 alleles (especially Z and S) produce variable AAT levels. Homozygous PiZZ causes severe deficiency and high disease risk; heterozygotes (e.g., MZ, SZ) have intermediate levels and modestly increased risk, especially with smoking or other lung insults.

Treatment focuses on slowing lung damage and managing complications. Key measures include smoking cessation, vaccinations, avoiding pollutants, bronchodilators/inhaled corticosteroids, pulmonary rehabilitation, oxygen therapy, and antibiotics for infections. Selected patients with emphysema receive regular intravenous augmentation with pooled human alpha‑1 antitrypsin. Liver disease is managed supportively and may require transplant in advanced cases. Genetic counselling and family screening are recommended.

Consider AAT testing if you have early-onset COPD or emphysema (especially before age 45–50), unexplained liver disease or persistent abnormal liver tests, bronchiectasis, or unexplained panniculitis. Also test if a close family member has known alpha‑1 antitrypsin deficiency, or if you have emphysema with little or no smoking history; results guide treatment and family screening.