<i>a <sub>1</sub>-ANTITRIPSIN: FUNCTIONAL CHARACTERISTICS AND GENETIC POLYMORPHISM </i>
а1-Antitripsin is a serin protease inhibitor specific mainly to neutrophylic elastase. The a <sub>1</sub>-antitripsin normal concentration is 200 to 400 mg/dl by nephelometry data. The Pi gene (proteinase inhibitor) is responsible for the a <sub>1</sub>-antitripsin production. The gene is highly polymorphic. M-allele present in most of population is a normal Pi gene variant. The Pi gene alleles causing the serum c <sub>1</sub>-antitripsin level reduction are called deficient. PiS and Z alleles are met most often. Multiple organs are involved in the pathologic process mostly lungs and liver being damaged. Because of the proteases inhibitors insufficiency the balance in the proteolysis - antiproteolysis system is changed. The blood c <sub>1</sub>-antitripsin low levels fail to provide complete inhibiting of the neutrophylic elastase, the lung tissue components are impaired by aggressive proteolytic enzymes and pulmonary emphysema develops. In Z-mutation carriers the c <sub>1</sub>-antitripsin molecules polymerize and accumulate in hepatocytes damaging them and causing development of neonatal cholestasis, juvenile hepatitis, cirrhosis, and hepatocellular carcinomas. The Pi gene variants expressing c <sub>1</sub>-antitripsin having changed characteristics are known, the serum concentration being within the normal range. The disease start, course and prognosis are determined in addition to the mutation variant by the environmental factors, way of life that can provoke the c <sub>1</sub>-antitripsin deficiency development and aggravation in clinically healthy persons. The population screening and genotyping programs allow reveal predisposition to c <sub>1</sub>-antitripsin deficiency development as well as perform that pathology primary and secondary prevetion.