Alpha-1 antitrypsin (AAT) deficiency is an inherited disorder that may cause lung and/or liver disease. First signs and symptoms of lung disease usually develop between the ages of 30 and 40 in smokers. The first signs of symptoms in non smokers usually develop between 40 and 55. These symptoms include shortness of breath following mild activity, reduced ability to exercise, and wheezing. Affected individuals often develop a lung disease called emphysema, making it difficult to breathe and produces a hacking cough. The appearance of emphysema and damage to the lungs is accelerated by smoking or exposure to tobacco smoke. Life expectancy may be normal for non-smokers. About 10 percent of infants with AAT deficiency develop liver disease, and about 15 percent of adults develop liver damage. Signs of liver disease or damage include a swollen abdomen, swollen feet or legs, and jaundice (yellowing of the skin and whites of the eyes). The risk of liver cancer is increased in all individuals with alpha-1 antitrypsin deficiency. AAT deficiency is caused by pathogenic variants in the SERPINA1 gene.