Alpha-1 antitrypsin deficiency (AATD) is a relatively rare genetic disorder, inherited in an autosomal codominant manner, that results in reduced serum AAT concentrations, with a consequent reduction in antielastase activity in the lungs, as well as an increased risk of diseases such as pulmonary emphysema, liver cirrhosis, and necrotizing panniculitis. The gene discussed is SERPINA1; the disease is alpha 1-antitrypsin deficiency.