Alpha-1 antitrypsin deficiency (AATD) is a recessive genetic disorder caused by single nucleotide variants (SNV) in the SERPINA1 gene encoding for alpha-1 antitrypsin (AAT), with the most common mutation being the E342K mutation (Z allele) that introduces an amino acid change from glutamic acid (E) coding for M-AAT to a lysine (K) coding for Z-AAT.