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Cerebral toxoplasmosis in a middle-aged man as first presentation of primary immunodeficiency due to a hypomorphic mutation in the CD40 ligand gene
  1. P F K Yong1,
  2. F A Post2,
  3. K C Gilmour3,
  4. D Grosse-Kreul1,
  5. A King4,
  6. P Easterbrook2,
  7. M A A Ibrahim1
  1. 1Department of Clinical Immunology, King’s College Hospital, London, UK
  2. 2Guy’s, King’s and St Thomas’ School of Medicine, London, UK
  3. 3Molecular Immunology, Great Ormond Street Hospital, London, UK
  4. 4Department of Neuropathology, King’s College Hospital, London, UK
  1. Dr Mohammad Ibrahim, Department of Clinical Immunology, King’s College Hospital, Denmark Hill, London SE5 9RS, UK; m.ibrahim{at}


Cerebral toxoplasmosis can occur outside the setting of advanced HIV immunodeficiency or drug-induced immunosuppression. A case of cerebral toxoplasmosis is reported in a previously healthy 41-year-old man who was found to have a genetic defect in CD40 ligand, resulting in the X linked hyper-IgM syndrome despite normal surface protein expression on flow cytometry. This highlights the fact that primary immunodeficiencies can first present late in life with a relatively mild phenotype and should be considered in the differential diagnosis of opportunistic infections in non-HIV infected patients; in addition, normal protein expression does not necessarily rule out hypomorphic mutations.

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  • Competing interests: None.

  • Patient consent: Informed consent has been obtained for the publication of the details in this report.