Alpha 1-antitrypsin deficiency
(A1AD) is a genetic disorder that causes defective production of alpha 1-antitrypsin leading to its decreased activity in the blood and lungs, and deposition of excessive abnormal A1AT protein in liver cells. The form and degree depend on whether the sufferer has one or two copies of the defective allele because it is a co-dominant trait. Severe A1AT deficiency causes panacinar emphysema
, through the uninhibited action of elastase in the alveoli. It is treated through avoidance of damaging inhalants and, in severe cases, by intravenous infusions of the A1AT protein or by transplantation of the liver or lungs.