Alpha-1 antitrypsin deficiency

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Alpha-1 antitrypsin deficiency is a hereditary disorder in which a lack or low level of the enzyme alpha-1 antitrypsin damages the lungs and liver.

Alpha-1 antitrypsin deficiency is caused by an inherited gene mutation.
Infants may develop jaundice and liver damage.
Cirrhosis can develop during childhood.
Adults commonly develop emphysema, with shortness of breath, wheezing, and coughing, and some adults develop cirrhosis.
Tests that measure the amount of the enzyme in the blood and that detect the gene mutations are used for diagnosis.
People with emphysema take drugs to improve breathing and sometimes receive infusions of alpha-1 antitrypsin by vein.
Some people need lung or liver transplants.

Alpha-1 antitrypsin is an enzyme produced by the liver that inhibits the action of other enzymes called proteases. Proteases break down proteins as part of normal tissue repair. Alpha-1 antitrypsin protects the lungs from the damaging effects of proteases.
Alpha-1 antitrypsin deficiency results from an inherited mutation in the gene that controls production and release of the enzyme. There are many subtypes of alpha-1 antitrypsin deficiency, but in all, levels of active enzyme in the blood are insufficient, the enzyme is structurally abnormal (and thus functions poorly), or both. Whites are affected more often than blacks or people of Asian or Hispanic ancestry.
The most common problems caused by the deficiency are

Liver damage
Emphysema (a form of chronic obstructive pulmonary disease, or COPD)

If the enzyme is structurally abnormal, it may clump in the liver, causing the liver to malfunction. In some people, liver malfunction leads to cirrhosis and to an increased risk of liver cancer.
The low levels of alpha-1 antitrypsin allow proteases to damage the lungs, resulting in emphysema. Emphysema is more common (and worse) in people who smoke. Emphysema in nonsmokers can be caused by alpha-1 antitrypsin deficiency.
Disorders of other organs sometimes occur. These disorders include inflammation of fat under the skin (panniculitis), life-threatening bleeding, aneurysms, ulcerative colitis, vasculitis, and kidney disease.