In healthy individuals, the lungs contain a natural enzyme called neutrophil elastase that, under normal circumstances, helps the lungs by digesting damaged, aging cells and bacteria. This process promotes healing of the lung tissue. Unfortunately for the lungs, however, these enzymes don't know when to stop, and eventually attack the lung tissue instead of helping it heal. That's where AAT comes in. By destroying the enzyme before it can cause actual damage to healthy lung tissue, the lungs proceed to function normally. When there is not enough AAT, however, the lung tissue will continue to be destroyed, which may lead to the chronic lung disease, emphysema.
How Can I Inherit AAT Deficiency?
When a child is born, he inherits two sets of AAT genes, one from each parent. The child will only have AAT deficiency if both sets of AAT genes are abnormal. If only one AAT gene is abnormal and the other is normal, then the child will be a "carrier" of the disease, but will not actually have the disease itself. If both sets of genes are normal, then the child will not be afflicted with the disease, nor will he be a carrier.If you have been diagnosed with AAT deficiency, it is important that you talk with your doctor about having other people in your family tested for the disease, including each of your children. If you do not have children, your doctor may recommend that you seek genetic counseling before you make that decision.
For more information on genetic counseling, call the Alpha-1 Association Genetic Counseling Center at 1-800-785-3177 or visit the Alpha-1 Foundation.
Statistics
AAT deficiency knows no boundaries and has been identified in virtually every population, culture and ethnic group. The American Lung Association estimates that there are 100,000 people in the United States who were born with AAT deficiency. Among the majority of these individuals, AAT related emphysema may be prevalent. Moreover, since AAT deficiency is often either underdiagnosed or misdiagnosed, as many as 3% of all emphysema cases related to AAT deficiency are never detected.
Worldwide, 116 million people are carriers of AAT deficiency. Of these, approximately 25 million live in the United States. While carriers do not actually have the disease themselves, they can pass the disease on to their children. With this in mind, the World Health Organization (WHO) recommends that all people with COPD, as well as adults and teenagers with asthma, be tested for AAT deficiency.
The risk of developing AAT related emphysema significantly increases for people who smoke. The American Lung Association states that smoking not only increases your risk for emphysema if you have AAT deficiency, but it can also decrease your lifespan by as much as 10 years.
Signs and Symptoms of AAT Deficiency
Because AAT related emphysema sometimes takes a backseat to more easily recognized forms of COPD, much effort has been made over the years to find ways to distinguish it. According to Chest, two major features of emphysema related to severe AAT deficiency should prompt suspicion of AAT related emphysema.
First, emphysema symptoms in non-AAT deficient individuals usually don't occur until the sixth or seventh decade of life. According to the American Lung Association, this is not true for people who have AAT related emphysema. For these folks, the onset of symptoms occurs much earlier, often between the ages of 32 to 41.
Another important feature that differentiates AAT related emphysema from its non-AAT deficient counterpart is the location in the lungs where the disease most frequently appears. In those who have AAT deficiency related emphysema, the disease is more prevalent in the lower part of the lungs, whereas in non-AAT related emphysema, the disease affects the upper lung region. Both of these features can help your healthcare provider make an accurate diagnosis.
The most common signs and symptoms of AAT deficiency emphysema are:
- Shortness of breath
- Wheezing
- Chronic cough and mucus production (chronic bronchitis)
- Recurring chest colds
- Jaundice
- Swelling of the abdomen or legs
- Decreased exercise tolerance
- Non-responsive asthma or year-round allergies
- Unexplained liver problems or elevated liver enzymes
- Bronchiectasis
Diagnosis and Testing
A simple blood test can tell your doctor if you have AAT deficiency. Because of the importance of early diagnosis, the University of South Carolina has developed a program, with the help of the Alpha-1 Foundation, that allows for free, confidential testing to those at risk for the disease.
Early diagnosis is critical because smoking cessation and early treatment may help slow the progression of AAT related emphysema.
For more information about testing, please contact the Alpha-1 Research Registry at the Medical University of South Carolina at 1-877-886-2383 or visit the Alpha-1 Foundation.
