Selective IgA deficiency most commonly presents with which feature?

Selective IgA deficiency most commonly presents with which feature?

• A. Recurrent mucosal infections; often asymptomatic; risk of anaphylaxis to IgA-containing products.
• B. Severe systemic infections
• C. Autoimmune diseases
• D. Isolated leukopenia

Answer: (A)

IgA is the main antibody at mucosal surfaces, so when selective IgA is deficient, the first line of defense at sinuses, airways, and gut is weakened. This leads to recurrent mucosal infections such as sinusitis, bronchitis, and GI infections, though many individuals may be asymptomatic because other immune mechanisms can compensate in some situations. A key clinical pitfall is the risk of anaphylaxis or severe reactions if an IgA-containing product (like certain blood products) is given, due to antibodies against IgA that some deficient individuals have formed. The other options describe patterns that are not typical of this condition: widespread systemic infections are not the usual presentation, autoimmune associations can occur but are not the defining feature, and isolated leukopenia is unrelated.

IgA is the main antibody at mucosal surfaces, so when selective IgA is deficient, the first line of defense at sinuses, airways, and gut is weakened. This leads to recurrent mucosal infections such as sinusitis, bronchitis, and GI infections, though many individuals may be asymptomatic because other immune mechanisms can compensate in some situations. A key clinical pitfall is the risk of anaphylaxis or severe reactions if an IgA-containing product (like certain blood products) is given, due to antibodies against IgA that some deficient individuals have formed. The other options describe patterns that are not typical of this condition: widespread systemic infections are not the usual presentation, autoimmune associations can occur but are not the defining feature, and isolated leukopenia is unrelated.