Emphysema & AAT Deficiency
Emphysema is a form of chronic obstructive pulmonary disease (COPD). Emphysema is caused by destruction of alveoli, which leads to reduced surface area for gas exchange. Emphysema also involves a loss of elasticity, which results in trapping of air in the lungs.
Individuals with alpha-1 antitrypsin (AAT) deficiency* are at risk for developing emphysema because of the role that naturally occurring AAT plays in protecting the lungs. Neutrophil elastase (NE), an enzyme which breaks down bacteria, can become destructive of lung tissue if it is not neutralized by AAT.
*Also known as Alpha-1, AAT Deficiency, AATD, A1-PI deficiency, alpha-1 proteinase deficiency, A1AD, or hereditary or genetic emphysema.
Individuals with alpha-1 antitrypsin deficiency may not have enough naturally occurring AAT to maintain the balance between AAT and NE, and so may have inadequate protection against the damaging effects of NE. This imbalance between AAT and NE can lead to AAT deficiency-related emphysema, sometimes referred to as hereditary emphysema. Not all individuals with AATD will develop symptomatic emphysema.
AAT-related emphysema results in permanent, progressive damage to the lungs which can become fatal if the progress is not slowed.1
Patients with AAT-related emphysema and typical emphysema often have similar clinical presentations. Key differentiating factors include age of onset, family history, and presence of extrapulmonary manifestations.
| Typical Emphysema | AAT-related Emphysema | |
|---|---|---|
| Not associated with extrapulmonary manifestations | May be associated with liver abnormalities and panniculitis | |
| Usually associated with heavy smoking history | May occur without smoking history (Individuals with AAT deficiency who do smoke may experience earlier onset of symptoms.) |
References
- American Lung Association. COPD Fact Sheet. http://www.lungusa.org/lung-disease/copd/resources/facts-figures/COPD-Fact-Sheet.html. Accessed June 16, 2011.
