Rare primary immunodeficiency characterized by the clinical triad of fulminant infectious mononucleosis (FIM), dysgammaglobulinaemia and lymphoma.
- SH2D1A gene (M/C, 80%):
- Encodes the adaptor molecule signalling Lymphocytic Activation Molecule (SLAM)‐associated protein (SAP)
- XIAP gene:
- Endcodes X‐linked inhibitor of apoptosis protein (XIAP).
Inability to eliminate Epstein-Barr virus (EBV)
Fulminant infectious mononucleosis
Development of B-cell tumours
Unique propensity of affected males to develop progressive lymphoproliferation, hepatosplenomegaly, cytopenias and erythrophagocytosis following Epstein–Barr virus (EBV) infection.
- Disease onset: 2·5 years
- T and B cell lymphoproliferation → secondary haemophagocytic lymphohistiocytosis (HLH)
- Aplastic anaemia
- Lymphoid vasculitis
- Pulmonary lymphoid granulomatosis
- Autoimmune features: Colitis and psoriasis
Common variable immunodeficiency (CVID)
- Normal B cell countin lymphoid tissues (vs Reduced B cells in XLP)
Myeloablative/reduced-intensity haematopoietic stem cell transplantation (SCT)
- Poor: 70% die before 10 years
- 96% mortality