Review Question - QID 104938

This patient has selective IgA deficiency. These patients have recurrent sinus and lung infections, milk allergies, and diarrhea and may present with anaphylaxis on exposure to blood products with IgA.

A disorder associated with IgA deficiency is Ataxia-telangiectasia, a congenital defect in DNA repair enzymes which may lead to the triad of cerebellar defects (ataxia), spider angiomas (telangiectasia), and IgA deficiency. Recall that IgA prevents attachment of bacteria and viruses to mucous membranes. It does not fix complement, however. IgA is secreted as a dimer but is found as a monomer in circulation. It is found in tears, saliva, mucus and breast milk (colostrum).

Latiff et al. note that the prevalence of IgA deficiency is about 1 in 500 in Caucasians and the majority are clinically asymptomatic. There is no specific treatment for patients with symptomatic IgA deficiency. Antibiotics are prescribed in those with acute infections.

Cunningham-Rundles discusses the physiology of IgA and IgA deficiency. Some IgA deficient individuals have a reduced antibody response to immunizations even when they have normal IgG and IgGM levels, and others have a deficient response to bacterial polysaccharides, thus increasing susceptibility to encapsulated pathogens.

Illustration A depicts the different immunoglobulins.

Incorrect Answers:
Answer 1: This would be expected in a patient with hyper-IgE syndrome (Job’s syndrome)
Answer 3: This would be expected in a patient with chronic mucocutaneous candidiasis.
Answer 4: This would be expected in a patient with Wiskott-Aldrich syndrome.
Answer 5: This would be expected in a patient with hyper-IgM syndrome