Alpha-1 Antitrypsin (AAT) protects the delicate tissues of the lungs by binding to neutrophil elastase, a protein released by white blood cells which digests bacteria and other foreign objects in the lungs. When a person who is deficient of AAT inhales irritants, or contracts a lung infection, the neutrophil elastase released in the lungs continues digesting irritants unchecked, eventually destroying healthy lung tissue. The eventual result of the destruction of healthy lung tissue by neutrophil elastase is emphysema.
However, Alpha-1 Antitrypsin Deficiency (AATD) emphysema (also known as "genetic" or "inherited" emphysema) is different than emphysema caused by smoking ("acquired" emphysema). In emphysema caused by smoking the damage usually affects the upper portion of the lungs. In the AATD patient, the lower regions of the lungs are first affected. With either cause, the lungs are hyperinflated due to air trapping caused by the destruction of the lung tissue, and the diaphragms are flattened due to the hyperinflation of the lungs.
Emphysema is a lung disease caused by the destruction of the delicate walls of small air sacs (alveoli). With this destruction, air sacs lose their elasticity and form larger, inefficient sacs that cannot properly exchange oxygen and carbon dioxide with the bloodstream. In addition, it becomes harder to breathe since each drawn breath inflates the lungs, but the lungs do not return to normal with the exhaled breath. This causes air to become trapped, leading to over-inflation of the air sacs. Emphysema caused by AATD is a progressive disease-the destructive action continues until the lungs can no longer bring in oxygen to the bloodstream.
AATD emphysema usually causes symptoms in people while they are in their 30s or 40s. While there is no cure for AATD (other than a liver transplant), there are treatments available for the symptoms, as well as augmentation therapy, which may slow down or halt the destruction. Patients with more severe or advanced AATD lung disease may be candidates for lung transplantation.
Many people with Alpha-1 also have chronic bronchitis. With this, the lung lining becomes swollen and congested with mucus, restricting air flow. The bronchi (air passages) often go into bronchospasms, which are contractions of the muscles which further reduce air flow. This often results in a chronic cough.