Alpha-1 antitrypsin (AAT) deficiency is a condition in which the body does not make enough of a protein that protects the lungs and liver from damage. The condition can lead to emphysema and liver disease.
AAT deficiency; Alpha-1 protease deficiency
Alpha-1 antitrypsin (AAT) is a type of protein called a protease inhibitor. AAT is made in the liver and it works to protect the lungs and liver.
AAT deficiency means there is not enough of this protein in the body. It is caused by a genetic defect. The condition is most common among Europeans and North Americans of European descent.
Adults with severe AAT deficiency will develop emphysema, often before age 40. Smoking can increase the risk of emphysema. Other patients have a higher level of AAT in their blood, and therefore have a less severe condition.
Persons with this deficiency may also develop liver disease.
Your doctor may suspect you of having this condition if you develop:
Emphysema before age 45
Emphysema but you have never smoked or been exposed to toxins
Emphysema and you have a family history of the condition
Liver disease and no other cause can be found
Liver disease and you have a family history of liver disease
Treatment for AAT deficiency involves replacing the missing AAT protein. The protein is given through a vein each week. This is only slightly effective at preventing more lung damage in patients without end-stage disease.
If you smoke, you need to quit.
Other treatments are also used for emphysema and cirrhosis.
Some people with this deficiency will not develop liver or lung disease.
Denis Hadjiliadis, MD, Associate Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.