alpha-1-antitrypsin

noun

al·​pha-1-an·​ti·​tryp·​sin -ˌwən-ˌant-i-ˈtrip-sən, -ˌan-ˌtī- 

: a trypsin-inhibiting serum protein which inhibits the digestive action of elastase on the tissues of the lungs and whose deficiency is associated with the development of emphysema

—abbreviation AAT