Alpha 1-antitrypsin deficiency is a genetic disorder that manifests itself in reduced levels of the alpha-1 protein in the blood. Alpha-1 is normally produced in the liver. But the gene mutation in patients with "alpha" causes the protein to have an abnormal form which does not exit the liver, thereby lowering the level of the protein in the blood.

The alpha-1 protein protects the body's tissues against enzymes that may be produced after inflammation, especially in the lungs. The effects of A1AD include chronic cough and emphysema, especially in those exposed to environmental irritants such as cigarette smoke.

The most severe cases occur when what is known as the "Z" gene is inherited from both parents, which results in very low alpha-1 levels in the blood. Milder cases occur when only one "Z" gene is inherited and some alpha-1 levels are present.

Liver disease can also develop due to the clogging of the liver with the defective alpha-1 proteins.