Antitrypsin deficiency is an inborn metabolic disorder caused by a deficiency of the antitrypsin component, alpha1 antitrypsin, in the blood, inherited through autosomal inheritance. Clinically, it often leads to neonatal hepatitis, cirrhosis, hepatocellular carcinoma and emphysema in infants and adults. Its pathogenesis is due to the presence of exogenous and endogenous proteases, such as bacterial toxins and proteases disintegrated by leukocytes, which have destructive effects on the liver and other organs. α1 trypsin can detoxify and resist these enzymes to maintain the integrity of tissue cells. When α1 trypsin is deficient, all of these enzymes can attack liver cells, especially in newborns with imperfect digestion and absorption in the intestinal lumen, and more macromolecules enter the bloodstream. α1 trypsin-deficient infants are more susceptible to liver damage. In addition, α1 trypsin has the function of regulating immune response, affecting the clearance of antigen-antibody-immune complexes, complement activation and inflammatory response, and inhibiting platelet aggregation and fibrinolysis.