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Alpha-1 antitrypsin deficiency (AATD) is an inherited condition that causes AAT proteins, which protect the lungs and other organs, to get trapped in the liver. This increases risks of both lung and liver disease, and it can cause early-onset emphysema.

AATD occurs most often in white people of European descent, although it can occur in any ethnic group. Estimates of people with AATD range from about one in every 1,600 to about one in every 5,000. Because people with AATD don’t always develop serious complications, they might not even know they have it.

The first symptoms of AATD usually occur between ages 20 and 40. Symptoms can include shortness of breath, wheezing, and reduced physical endurance, as well as lung infections, vision problems, tiredness, weight loss, and a rapid heartbeat upon standing.

People with severe AATD can develop emphysema early in life (between ages 40 and 50). Emphysema causes a chronic cough, trouble breathing, and wheezing, which is why AATD is often misdiagnosed as asthma.

Other potential complications of AATD include cirrhosis and other liver diseases, often diagnosed in infancy and early childhood. Rarely, people with AATD can develop a painful skin disease called necrotizing panniculitis.

People with AATD are more susceptible to life-threatening lung diseases. Smoking and exposure to tobacco smoke are the most significant risk factors. Exposure to toxic substances, dust, and fumes are also risk factors.

People with AATD inherit the condition from their parents. The most common defective genes tied to AATD are known as S and Z, while M is considered normal. So, a person without AATD will have two M genes (MM). Generally, people with one faulty AAT gene are carriers of the disorder, while people with two faulty AAT genes have the disorder. However, even people with two faulty genes might never have complications or even know they have AATD. The table below shows how AAT genes relate to circulating AAT protein levels and associated lung disease.

AAT Gene Diagnosis Serum AAT Levels: Risk of Emphysema
μM mg/dL
MM Normal 20-48 150-350 Normal (low)
MS Carrier Unknown Unknown Low
MZ Carrier 17-33 90-120 Possibly increased
SS AAT Deficient 15-33 100-200 Unknown
SZ AAT Deficient 8-16 75-120 Likely increased
ZZ AAT Deficient 2.5-7 20-45 Definitely increased
Z-Null AAT Deficient Unknown Unknown Definitely increased
Null-Null AAT Deficient 0 0 Definitely increased

There is no cure for AATD, but the related lung diseases can be treated. Importantly, not smoking (or quitting smoking) will help delay or prevent lung diseases. A healthy diet and a suitable level of regular physical activity will help maintain lung function.

Alpha-1 augmentation therapy might be prescribed in severe cases to help slow a decline in lung function. Augmentation therapy is the infusion of an alpha-1 proteinase inhibitor (A1Pi) into the bloodstream. This can be administered safely at home with the help of a nurse. Diplomat Specialty Infusion Group offers multiple brands of A1Pi treatments—including Aralast®, Glassia®, and Zemaira®—and can provide qualified in-home nursing service.

Source: National Heart, Lung, and Blood Institute

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