Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder that results in a deficiency of a protein called alpha-1 antitrypsin (AAT). This protein is primarily produced in the liver and helps protect the lungs from inflammation caused by infection and inhaled irritants such as tobacco smoke.

Without adequate amounts of AAT, individuals are more susceptible to lung diseases like chronic obstructive pulmonary disease (COPD). AATD can also affect the liver, leading to conditions like jaundice, cirrhosis, and liver failure in severe cases.