Alpha-1-antitrypsin (AAT), a 394 amino acid, 52 kDa glycoprotein synthesized by the liver, is the most abundant circulating serine protease inhibitor with normal serum concentration of 85–250 mg/dL.1–3 AAT deficiency, caused by mutations in the AAT gene coding4–6 on the long arm of human chromosome 14 (locus 14q32.1),7 is a genetic condition that increases the risk of developing a variety of diseases including pulmonary emphysema, cirrhosis of the liver and gut disease. The gene discussed is SERPINA1; the disease is cirrhosis of liver.