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Selective IgA deficiency
Related Subjects: |X linked Agammaglobulinaemia (Bruton) |X-linked lymphoproliferative disease (Children) |Chediak Higashi syndrome |Common variable immunodeficiency |Severe combined immunodeficiency disorders |DiGeorge syndrome (thymic aplasia) |Selective IgA deficiency |Wiskott-Aldrich syndrome (Children) |T lymphocytes
May lead to a falsely negative anti-endomysial antibody when screening for Coeliac disease. Patients may also have an immune reaction to IVIG and should be screened beforehand.
📖 About
- Selective IgA Deficiency (sIgAD) = failure of B cells to mature into IgA-secreting plasma cells.
- Most common primary immunodeficiency (≈ 1 in 600 in Caucasians).
- Inheritance is often autosomal dominant with incomplete penetrance.
- IgA deficiency may rarely be acquired (e.g. due to phenytoin, sulfasalazine, immunosuppressants).
🩺 Clinical Features
- Often asymptomatic – many cases found incidentally on immunoglobulin testing.
- Recurrent respiratory & GI infections: sinusitis, otitis media, pneumonia, chronic diarrhoea (Giardia).
- Allergy/atopy: asthma, eczema, allergic rhinitis more common.
- Autoimmunity: ↑ risk of SLE, rheumatoid arthritis, autoimmune thyroid disease, coeliac disease.
- Transfusion reactions: risk of anaphylaxis if transfused with blood products containing IgA.
🔎 Investigations
- Serum IgA: undetectable or < 0.07 g/L (< 10 mg/dL).
- IgG & IgM: normal (helps distinguish from CVID).
- Coeliac screening: may have false-negative IgA-based tTG or EMA tests → use IgG-based assays (tTG-IgG, DGP-IgG).
⚕️ Management
- No curative treatment; most patients monitored only.
- Prompt antibiotics for infections; prophylactic antibiotics in severe recurrent infections.
- Avoid blood products containing IgA (use washed red cells or IgA-depleted products).
- IVIG generally not used (low IgA content in standard products, but risk of anti-IgA anaphylaxis).
- Vaccinate against encapsulated organisms (pneumococcus, H. influenzae, meningococcus).
💡 Teaching Pearls:
- Most common immunodeficiency, often asymptomatic.
- Think of it in patients with recurrent sinopulmonary infections + coeliac-like symptoms but negative IgA serology.
- Always warn patients about transfusion anaphylaxis risk.
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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