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  • Primary immune deficiency diseases (PIDDs) are characterized by an increased susceptibility to infections, often associated with autoimmunity and inflammation, and an increased risk of malignancies because of impaired immune homeostasis and surveillance.

  • Clinical presentation varies depending on the nature of the immune defect. The principal clinical features of PIDDs are listed in Table 51–1.

  • With the exception of immunoglobulin (Ig) A deficiency and DiGeorge syndrome, PIDDs are generally rare, with a prevalence of approximately 1 in 10,000 to 50,000 individuals.

  • Most forms follow Mendelian inheritance and present in childhood; however, some, such as common immunodeficiency, have a multifactorial origin and appear later in life.

  • The diagnostic approach is based on a detailed family and clinical history, physical examination, and appropriate laboratory tests. Laboratory results should be compared with age-matched control values because white blood cell counts, lymphocyte subsets, complement components, Ig levels, and antibody production (especially to polysaccharide antigens) undergo significant changes and progressive maturation in the first years of life.

  • Recognition of PIDDs is essential to start optimal therapies at an early age.



X-Linked and Autosomal Recessive Agammaglobulinemia

Definition and Genetic Features

  • This deficiency is caused by a maturation defect in B-cell development.

  • X-linked agammaglobulinemia (XLA) is the result of a mutation in the Bruton tyrosine kinase (BTK) gene.

  • Autosomal recessive agammaglobulinemia is the result of mutations in genes relevant to immunoglobulin (Ig) heavy or light chains (ie, IGHM, IGLL1, CD79a, CD79b, or the B-cell adaptor molecule, BLINK).

Clinical Features

  • XLA and autosomal recessive agammaglobulinemia have similar clinical features: low Ig levels, decreased B cells, and recurrent infections.

  • Normal levels of IgG at birth are a result of transfer from maternal circulation. Thus, affected individuals are usually asymptomatic for the first few months of life.

  • Symptoms and signs vary and may be mild or severe. The condition first develops between 4 and ...

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