The importance of IgA comes from studies on patients with Primary Antibody Deficiencies (PAD), where the impaired IgA production, and IgA antibody-mediated responses, are associated to the susceptibility to respiratory and gastrointestinal infections and their recurrence (Hammarström et al., 2000; Tangye et al., 2020), to upper respiratory tract colonization (Pulvirenti et al., 2020a), and to the risk to develop chronic respiratory diseases (Quinti et al., 2011). The gene discussed is CD79A; the disease is digestive system infectious disorder.