Severe combined immunodeficiency: Difference between revisions
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== Background == |
== Background == |
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=== Epidemiology === |
=== Epidemiology === |
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| − | * Most common form of severe primary immunodeficiency |
+ | * Most common form of severe [[primary immunodeficiency]] |
=== Pathophysiology === |
=== Pathophysiology === |
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* Many genetic abnormalities can lead to this condition, and may cause related defects in B and NK cell lines |
* Many genetic abnormalities can lead to this condition, and may cause related defects in B and NK cell lines |
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* However, given that T-cells are required for B-cell function, all SCID patients are functionally B-cell deficient |
* However, given that T-cells are required for B-cell function, all SCID patients are functionally B-cell deficient |
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| + | |||
| + | == Clinical Manifestations == |
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| + | |||
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| + | * In adulthood, diagnosis is based on flow cytometry to T cell count, and T cell response to mitogens (see Definition, below) |
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=== Definition === |
=== Definition === |
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* '''Hypomorphic SCID''' is less severe, with a normal number of T-cells, but with T-cell function <30% compare to controls |
* '''Hypomorphic SCID''' is less severe, with a normal number of T-cells, but with T-cell function <30% compare to controls |
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| − | == |
+ | == Management == |
| + | * Initially treated supportively with management of infections and replacement of immunoglomubins |
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| − | |||
| + | * Protective isolation in hospital with positive pressure rooms |
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| ⚫ | |||
| + | * Antibiotic and antifungal prophylaxis to reduce frequency and severity of infections |
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| + | ** Commonly-used antibiotics include [[sulfisoxazole]], [[amoxicillin]], [[trimethoprim-sulfamethoxazole]], or [[azithromycin]] |
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| + | * Avoid live-attenuated vaccines, but can continue to give killed or subunit vaccines (though they may not mount much response) |
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| + | * Definitive treatment is [[hematopoietic stem cell transplantation]], ideally from HLA-identical sibling |
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| + | * Gene therapy is an area of active research |
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== Prognosis == |
== Prognosis == |
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Latest revision as of 08:19, 2 August 2020
Background
Epidemiology
- Most common form of severe primary immunodeficiency
Pathophysiology
- No or almost no T-cells, and any that exist do not work properly
- Many genetic abnormalities can lead to this condition, and may cause related defects in B and NK cell lines
- However, given that T-cells are required for B-cell function, all SCID patients are functionally B-cell deficient
Clinical Manifestations
Diagnosis
- Usually diagnosed at birth with newborn screen containing a TREC (T-cell receptor excision circles) assay
- In adulthood, diagnosis is based on flow cytometry to T cell count, and T cell response to mitogens (see Definition, below)
Definition
- T-cell count <300 cells/μL and no T-cell response to mitogens (<10% compared to controls)
- Hypomorphic SCID is less severe, with a normal number of T-cells, but with T-cell function <30% compare to controls
Management
- Initially treated supportively with management of infections and replacement of immunoglomubins
- Protective isolation in hospital with positive pressure rooms
- Antibiotic and antifungal prophylaxis to reduce frequency and severity of infections
- Commonly-used antibiotics include sulfisoxazole, amoxicillin, trimethoprim-sulfamethoxazole, or azithromycin
- Avoid live-attenuated vaccines, but can continue to give killed or subunit vaccines (though they may not mount much response)
- Definitive treatment is hematopoietic stem cell transplantation, ideally from HLA-identical sibling
- Gene therapy is an area of active research
Prognosis
- Uniformly fatal in childhood unless treated
