[COPD and alpha-1-antitrypsin deficiency]

Abstract

Alpha-1-antitrypsin deficiency (AATD) is the main genetic factor related to the development of emphysema. This protein has numerous variants, some of which are clinically relevant because their anomalous conformation implies that they fail to reach the target organs as they are polymerized in the hepatocyte. The main abnormal variant is PiZ. In a small percentage of individuals, the accumulation of Z polymers in the liver leads to the development of liver disease. The lack of AATD in the lung favors the development of emphysema, since the proteolytic effect of elastases - the main biological function of AATD - is not counteracted. In Spain, approximately 400 persons are diagnosed with severe AATD deficiency, representing less than 10 % of those expected by epidemiological studies. The principal prognostic factor in these patients is forced expiratory volume in one second (FEV(1)), which is affected mainly by exposure to tobacco smoke. Thus, life expectancy in nonsmokers is similar to that in the general population while lung function decreases faster in smokers than in other patients with chronic obstructive pulmonary disease (COPD). The treatment of the lung disease is the same, although exogenous AATD augmentation is indicated when lung function deteriorates.