DEAR MAYO CLINIC: A family friend was recently diagnosed with emphysema, but he never smoked and was told that his condition was caused by alpha-1. What is this, and how is it diagnosed?

ANSWER: Emphysema is one of a group of lung diseases, including chronic bronchitis, that makes up chronic obstructive pulmonary disease, or COPD. Tobacco smoking tops the list of emphysema risk factors. Less common risk factors include long-term exposure to dust or fumes. But there also are rare inherited risk factors, including alpha-1 (also called alpha-1 antitrypsin deficiency or AAT deficiency).

Emphysema involves long-term, permanent damage to the tiny clusters of air sacs (alveoli) in the lungs, where oxygen is absorbed into the bloodstream and carbon dioxide is released to be exhaled. Alveoli tissues are normally elastic, but emphysema results from destruction of the elastic tissue. This makes it harder to move air and, ultimately, results in shortness of breath that gets progressively worse over time.

Alpha-1 is diagnosed with a simple blood test. Normally, large amounts of the alpha-1 antitrypsin protein are made in the liver, released into the bloodstream and distributed to the body. This protein helps protect the lungs from damage and preserves the elasticity of lung tissues.

In those who have alpha-1 antitrypsin deficiency, an abnormal protein is made and it isn't fully released by the liver into the bloodstream. Thus, the lungs lose a major protective element and become susceptible to emphysema -- even in people who have never smoked and had only limited exposure to other lung irritants. For those who do smoke and have alpha-1 antitrypsin deficiency, smoking can greatly accelerate the damage that leads to emphysema. Moreover, buildup of the abnormal alpha-1 antitrypsin protein in the liver also can lead to permanent liver damage (cirrhosis), and is associated with liver cancer.

Breathing tests or chest imaging may be used to determine the severity of emphysema due to alpha-1 antitrypsin deficiency. Not everyone with the deficiency gets emphysema, so breathing tests and imaging can be important.

Alpha-1 protease inhibitors are a recent development in the treatment of alpha-1 antitrypsin deficiency. These inhibitors are infused blood products taken from healthy individuals that increase alpha-1 antitrypsin levels in the bloodstream. The therapy may slow lung damage, but can't reverse damage. It's very expensive, commonly involves weekly infusions and typically is available only to those who meet certain criteria.

A free, confidential testing program is available for family members of someone with alpha-1 antitrypsin deficiency. Details can be found on the Alpha-1 Foundation website found at www.alpha1.org. (adapted from Mayo Clinic Health Letter) -- Michael J. Krowka, M.D., Pulmonary & Critical Care Medicine, Rochester, Minn.

(Mayo Clinic Q & A is an educational resource and doesn't replace regular medical care. E-mail a question to MayoClinicQ&A@mayo.edu. For more information, visit www.mayoclinic.org.)

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