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
Causes, incidence, and risk factors
Alpha-1 antitrypsin (AAT) is a type of protein called a "protease inhibitor." It 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.
Studies show that AAT deficiency may be more common than was once thought.
Adults with severe deficiency will develop emphysema, often before age 40. Smoking can increase the risk of emphysema. Other patients can have higher levels of AAT in their blood, and therefore have a less severe condition.
Persons with this deficiency may also develop liver disease.
Shapiro SD, Reilly JJ Jr, Rennard SI. Chronic bronchitis and emphysema. In: Mason RJ, Broaddus CV, Martin TR, et al. Murray & Nadel's Textbook of Respiratory Medicine. 5th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 39.
Silverman EK, Sandhaus RA. Alpha-1 antitrypsin deficiency. N Engl J Med 2009;360:2749-2757.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.