Abstract
Alpha-1-antitrypsin (AAT) deficiency (AATD) is one of the most common genetic disorders. Most people carry two copies of the wild-type M allele of the SERPINA1 gene, which encodes AAT, and have normal blood concentrations of AAT.
Ninety-five percent of cases of severe AAT deficiency result from the homozygous Glu342Lys substitution (Z allele), which is present in 1 in 25 persons of European descent. Mild AAT deficiency is usually due to the Glu264Val mutation (S allele).
AAT is synthesized in the liver and secreted into the blood. Its primary role is to protect lung tissue from neutrophil elastase attack.
Point mutations can lead to the retention of AAT in the liver, leading to liver fibrosis and cirrhosis due to proteotoxic stress ("gain of function"), whereas the lack of circulating AAT predisposes homozygotes with severe deficiency to early onset of pulmonary emphysema ("loss of function"). This article reviews current knowledge of the pathophysiology of AAT deficiency, and its diagnostic options and discusses treatment options for pulmonary and novel treatment strategies in liver disease.
