Q: My doctor has urged me to stop smoking because low levels of some enzyme in my blood show that I am at high risk to develop lung disease. Could you help me to understand the problem?
A: Undoubtedly your doctor has found you have low levels of the enzyme alpha-antitrypsin (AAT).A deficiency of AAT is a fairly common inherited disorder associated with an increased tendency to develop emphysema, a chronic lung disease that leads to increasing shortness of breath as it progresses. Emphysema is caused by destruction of the small air sacs and loss of elasticity in the lungs. As a result, the small air passages tend to collapse and obstruct the flow of air, especially when breathing out.
Although the cause of emphysema is not fully understood, it is believed that enzymes that break down proteins damage the elastic tissue in the lungs by destroying its major protein, elastin. White blood cells in the lower respiratory tract release the enzyme that breaks down elastin, called elastase, and its destructive action is normally blocked by AAT.