Introduction
Clinical presentations of SCID
Classical SCID
Classical SCID | Omenn syndrome | Atypical SCID |
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Present in infancy | Present in infancy | Present >12 months of age |
Persistent viral respiratory +/− gastrointestinal infection | Erythroderma | Recurrent, severe, prolonged viral infection |
Pneumocystis jiroveci pneumonitis | Alopecia | bronchiectasis |
Disseminated BCG infection | Hepatosplenomegaly | Autoimmune cytopenias |
Failure to thrive | Massive lymphadenopathy | Failure to thrive |
Superficial candidiasis | Inflammatory pneumonitis/enteritis | Granulomatous cutaneous lesions |
Maternofoetal graft versus host disease | Raised IgE | EBV-associated lymphoproliferation |
Absent lymphoid tissue | Eosinophilia | Partial or restricted antigen-specific antibody responses |
Absent immunoglobulins | Lymphocytosis | Lymphopenia |
Absent T lymphocytes |
Omenn syndrome
Atypical SCID
Other forms of SCID
Stepwise diagnostics for SCID
Flow cytometric immunophenotyping of peripheral blood
Gene defects and disease mechanisms in T−B+ SCID
Gene defects and disease mechanisms in T−B− SCID
Detailed analysis of T cells potentially present in patients suspected for having typical or atypical SCID
Analysis of protein expression of candidate genes
Flow cytometric analysis of precursor B cell compartment in bone marrow
Sequence analysis of candidate genes
Supportive management
Curative therapy
Concluding remarks
Learning points
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▪ SCID is one of the most severe forms of PID and is a life-threatening paediatric emergency.
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▪ The molecular basis of most forms of SCID is now recognized.
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▪ Early careful liaison with the immunology laboratory will enable the most appropriate investigations to be performed.
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▪ Atypical, later presentation of patients with partial gene function is increasingly described.
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▪ Atypical SCID should be considered in patients presenting with unusual, severe or recurrent infections.