The SERPINA1 gene encodes the protein alpha-1 antitrypsin and is localized to chromosome 14q32. Multiple mutations have been identified, of which rs289299474 and rs17580 are the most common causes of severe alpha-1 antitrypsin deficiency, which may result in lung or liver disease. Symptoms are shortness of breath, wheezing, increased risk of lung infections, COPD, emphysema, cirrhosis and liver failure. One defective allele results in a milder form of the disease than two mutated alleles and disease severity is also dependent on the allele.