The idea originally derived from mere theoretical assumptions including reports of patients with concomitant AATD and hypogammaglobulinemia [22, 23], coexistence of bronchiectasis/emphysema in patients with either AATD or CVID [28], and the local proximity of the genes for the immunoglobulin heavy chain and AAT [29]. This evidence concerns the gene SERPINA1 and common variable immunodeficiency.