Alpha1-antitrypsin (AAT) deficiency, also known as Alpha-1, is a genetic (inherited) disorder that causes significant reduction in the naturally occurring blood protein alpha1-antitrypsin. A low level of alpha1-antitrypsin allows certain enzymes to attack healthy tissues in the body, primarily in the lungs. To replace missing or reduced levels of AAT, physicians often prescribe "augmentation" therapy with an alpha1-proteinase inhibitor.
