A1AD related emphysema is caused by an inherited lack of the protein alpha1-antitrypsin (AAT). In healthy individuals, AAT protects the lungs from neutrophil elastase, a natural enzyme that helps fight bacteria and eliminate dead lung tissue. However, this enzyme can also damage lung tissue if not neutralized by AAT.
If allowed to progress, this type of emphysema can become chronic and the tissues of the lungs continues to be destroyed. Without treatment, the condition can be fatal.
People inherit two AAT genes, one from each parent. A person can have an AAT deficiency only if he or she inherits two abnormal genes. People who have only one abnormal gene and one normal AAT gene are "carriers" but they do not have the disease. Their AAT levels may be lower than normal, but not as low as the deficiency state and are not generally thought to affect one's health. Fortunately,there is a test for determining if a person is a carrier or is AAT deficient. This test is called phenotyping.
Studies indicate that there are 50,000 to 100,000 Americans who were born with AAT deficiency. Of this group, A1AD related emphysema afflicts an estimated 20,000 to 40,000 people. If AAT deficient individuals also smoke, their risk of developing emphysema is much greater than the average person's.
One cause of lung damage is an enzyme produced by some of the body's white blood cells called neutrophil elastase. Neutrophil elastase is released by the white blood cells during times of inflammation. This action is normally helpful and neurtalized by the protein AAT produced in the liver. In some people, whose livers do not produce enough protective AAT. In these people, the neutrophil elastase attacks the walls of the lungs causing irreversible damage.
Fortunately, most people with A1AD related emphysema do not completely lack the protein. Instead, they do not have enough of the protein to neutralize the action of neutrophil elastase. Since this disease occurs in the lower lung areas, it is easier to diagnose than many other conditions.
The condition can be diagnosed by a simple blood test. This test determines if a person has low levels of the protective protein AAT. Approximately one in 2,500 people has this inherited deficiency. Most of them are of Northern European descent.
It is critical to detect AAT deficiency as early as possible because smoking cessation is necessary to slow the progression of emphysema. Treatment may also slow the progression of the disease.
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