An 8-month-old male infant is admitted to the hospital because of a bacterial respiratory infection. The infant responds to appropriate antibiotic therapy, but is readmitted several weeks later because of severe otitis media. Over the next several months, the infant is admitted to the hospital multiple times for recurrent bacterial infections. Workup reveals extremely low serum antibody levels. The infant has no previous history of viral or fungal infections. The most likely diagnosis for this infant is
In X-linked agammaglobulinemia of Bruton, B cells are absent but numbers and function of T cells are normal. This abnormality results from defective maturation of B lymphocytes beyond the pre-B stage. This maturation defect leads to decreased or absent numbers of plasma cells, and therefore immunoglobulin levels are markedly decreased. Male infants with Bruton's disease begin having trouble with recurrent bacterial infections at about the age of 9 months, which is when maternal antibodies are no longer present in the affected infant. Therapy for Bruton's disease consists primarily of IV gamma globulin. Isolated deficiency of IgA is probably the most common form of immunodeficiency. It is due to a block in the terminal differentiation of B lymphocytes. Most patients are asymptomatic, but some develop chronic sinopulmonary infections. Patients are prone to developing diarrhea (Giardia infection) and also have an increased incidence of autoimmune disease, such as Hashimoto's thyroiditis. In patients with chronic granulomatous disease (CGD), the neutrophils and macrophages have deficient H2O2production due to abnormalities involving the enzyme NADPH oxidase. These individuals have frequent infections that are caused by catalase-positive organisms, such as S. aureus, because the catalase produced by these organisms destroys the little hydrogen peroxide that is produced DiGeorge's syndrome is a T cell-deficiency disorder that results from hypoplasia of the thymus due to abnormal development of the third and fouh pharyngeal pouches. The parathyroid glands are also abnormal, and these individuals develop hypocalcemia and tetany. Congenital hea defects are also present. Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition.
Isolated IgA deficiency
X-linked agammaglobulinemia of Bruton
Chronic granulomatous disease
DiGeorge's syndrome
miscellaneous