Diagnostic approach of hypogammaglobulinemia in infancy

Primary B‐cell immunodeficiency is the most frequent immune defect in infancy. Selective absence of serum and secretory immunoglobulin IgA is the most common, with rates ranging from 1/333 persons to 1/16 000, among different races. By contrast, it has been estimated that hypo/agammaglobulinemia occurs with a frequency of 1/50 000 persons. Patients with antibody deficiency are usually recognized because they have recurrent infections with encapsulated bacteria or a history of failure to respond adequately to antibiotic treatment. However, some individuals, mainly those affected by IgA deficiency (SIgAD) or transient hypogammaglobulinemia of infancy , may have few or no infections.