Hyper IgM syndrome
🧪 Hyper IgM Syndrome ➝ rare immunodeficiency with high IgM but low IgG, IgA, IgE.
⚠️ Patients are prone to opportunistic infections (e.g. PJP) and have an increased risk of lymphoma and other cancers.
ℹ️ About
- 🧬 Hyper IgM syndrome is a rare primary immunodeficiency.
- 🔼 IgM elevated, but ❌ IgG, IgA, IgE are absent or very low.
- 💉 Leads to recurrent bacterial & opportunistic infections, plus malignancy risk.
🧬 Aetiology
- Genetic forms:
- 🧑🧒 X-linked (most common) ➝ CD40 ligand gene mutation, primarily in boys.
- 🧬 Autosomal recessive ➝ defects in class-switch recombination pathways, affect both sexes.
- Acquired forms:
- 💊 Secondary to drugs (e.g. phenytoin).
- 🩸 Associated with malignancies such as leukaemia.
🩺 Clinical Features
- 📉 Failure to thrive ➝ poor growth, recurrent illness.
- 🫁 Frequent respiratory infections (pneumonia, sinusitis, otitis media).
- 🌾 Chronic diarrhoea and weight loss (GI involvement).
- ⚠️ Opportunistic infections ➝ especially Pneumocystis jirovecii pneumonia (PJP).
🔎 Differentials
- 🧪 Common Variable Immunodeficiency (CVID).
- 🧬 Severe Combined Immunodeficiency (SCID).
- Other primary immunodeficiencies.
🧪 Investigations
- 📊 Immunoglobulin profile: High IgM, low/absent IgG, IgA, IgE.
- 🩸 Neutropenia in some patients ➝ worsens infection risk.
💊 Management
- 💊 Antibiotics ➝ prompt treatment of infections.
- 🛡️ PJP prophylaxis (e.g. co-trimoxazole).
- 💉 Immunoglobulin replacement therapy ➝ IV/SC IgG infusions to prevent infections.
- 🌱 Stem cell transplantation ➝ potential curative option in severe forms.
📚 References
✏️ Revisions
- ⚡ Early recognition and aggressive management ➝ prevents life-threatening infections and complications.