Indeed, while IgA deficiency is thought to be partially compensated by increases of mucosal and serum levels of other antibody classes such as IgM or IgG (52), the underrepresentation in IgA deficient patients of some sIgA-coated species found in normal microbiota suggests a non-redundant role of sIgA in bacterial colonization (53). This evidence concerns the gene CD79A and hyperinsulinemic hypoglycemia, familial, 4.