X-linked infantile hypogammaglobulinemia
X-linked infantile hypogammaglobulinemia: Excerpt from Professional Guide to Diseases (Eighth Edition)
X-linked infantile hypogammaglobulinemia is a recessive, congenital disorder in which all five immunoglobulins (Ig) — IgM, IgG, IgA, IgD, and IgE — and circulating B cells are absent or deficient but T cells are intact. It’s also called Bruton’s agammaglobulinemia and X-linked agammaglobulinemia. Affecting males almost exclusively, this disorder causes severe, recurrent infections during infancy. Prognosis is good with early treatment, except in infants who develop polio or persistent viral infection. Infection usually causes some permanent damage, especially in the neurologic or respiratory system.
Causes and incidence
In this disease, B cells and B-cell precursors may be present in the bone marrow and peripheral blood, but a mutation in the B-cell protein tyrosine kinase causes failure of the B cells to mature and to secrete immunoglobulin. In the absence of protective immunoglobulins, the affected individual develops repeated infections. Worldwide, malnutrition is the primary cause of antibody disorders.
Humoral immune deficiencies account for 50% of all primary immunodeficiencies. IgA deficiency is the most common antibody deficiency symdrome, followed by common variable immunodeficiency (CVID). The incidence of these two disorders is 1 in 700 persons.Selective IgM deficiency is rare. IgG4 deficiency occurs in 10% to 15% of the population.
Signs and symptoms
Typically, the infant with X-linked hypogammaglobulinemia is asymptomatic until age 6 months, when transplacental maternal immunoglobulins that provided immunity have been depleted. He then develops recurrent bacterial otitis media, pneumonia, dermatitis, bronchitis, and meningitis — usually caused by pneumococci, streptococci, Haemophilus influenzae, or other gram-negative organisms. Purulent conjunctivitis, abnormal dental caries, and polyarthritis resembling rheumatoid arthritis may also occur. Severe malabsorption associated with infestation by Giardia lamblia may retard development. Despite recurrent infections, lymphadenopathy and splenomegaly are usually absent.
Diagnosis
Diagnosis of X-linked hypogammaglobulinemia can be especially difficult because recurrent infections are common even in normal infants (many of whom don’t start producing their own antibodies until age 18 to 20 months). Immunoelectrophoresis and quantitative immunoglobulins (nephelometry) confirm decreased levels, or a total absence, of IgM, IgA, and IgG in the serum. IgG is usually less than 200 mg/dl, and IgA and IgM are almost unmeasurable. However, diagnosis by this method usually isn’t possible until the infant is 9 months old. Antigenic stimulation confirms an inability to produce specific antibodies, although cellular immunity remains intact.
Treatment
Treatment aims to prevent or control infections and to boost the patient’s immune response. Injection of immune serum globulin (gamma globulin, IV Ig) helps maintain immune response. Because these injections are painful, give them deep into a large muscle mass, such as the gluteal or thigh muscles, and massage well. If the dosage is more than 1.5 ml, divide it and inject it into more than one site; for frequent injections, rotate the injection sites. Because immune globulin is composed primarily of IgG, the patient may also need fresh frozen plasma infusions to provide IgA and IgM. Mucosal secretory IgA can’t be replaced by therapy, resulting in crippling pulmonary disease in many patients.
Judicious use of antibiotics also helps combat infection; in some cases, chronic broad-spectrum antibiotics may be indicated. During acute infection, monitor the patient closely. Maintain adequate nutrition and hydration. Perform chest physiotherapy if required.
Special considerations
❑ Carefully explain all treatment measures, and make sure the patient and his family understand the disorder.
❑ Teach the patient and his family how to recognize early signs of infection and counsel them to report such signs promptly. Advise them to have cuts and scrapes cleaned immediately. Warn them to avoid crowds and people who have active infections.
❑ Suggest genetic counseling if parents have questions about vulnerability of future offspring.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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