Worldwide, the most common pathogenic AATD variants are the S (c.863A > T; p.Glu288Val) and Z (c.1096G > T; p.Glu366Lys) variants, which express approximately 50–60% and 10–20% of normal AAT levels, respectively [15]. The gene discussed is SERPINA1; the disease is alpha 1-antitrypsin deficiency.