Wiskott-Aldrich syndrome: Difference between revisions
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===Secondary Prevention=== | ===Secondary Prevention=== | ||
Secondary preventive measures of wiskott aldrich syndrome are similar to primary prevention. | |||
==References== | ==References== | ||
Revision as of 14:48, 8 August 2018
| Wiskott-Aldrich syndrome | |
| ICD-10 | D82.0 |
|---|---|
| ICD-9 | 279.12 |
| OMIM | 301000 |
| DiseasesDB | 14176 |
| MeSH | D014923 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chandrakala Yannam, MD [2]
Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [3]
Synonyms and keywords: Aldrich syndrome
Patient Informtion
Overview
Wiskott-Aldrich syndrome (WAS) is a rare X-linked recessive disease characterized by eczema, thrombocytopenia (low platelet counts), immune deficiency, and bloody diarrhea (due to the low platelet counts). It is also sometimes called the eczema-thrombocytopenia-immunodeficiency syndrome in keeping with Aldrich's original description in 1954.[1] The WAS-related disorders of X-linked thrombocytopenia (XLT) and X-linked congenital neutropenia (XLN) may present similar but less severe symptoms and are caused by mutations of the same gene.
Historical Perspective
The syndrome is named after Dr Robert Anderson Aldrich, an American pediatrician who described the disease in a family of Dutch-Americans in 1954, and Dr Alfred Wiskott, a German pediatrician who first noticed the syndrome in 1937.[2] Wiskott described three brothers with a similar disease, whose sisters were unaffected. In 2006 a German research group analysed family members of Wiskott's three cases, and surmised that they probably shared a novel frameshift mutation of the first exon of the WAS gene.[3]
Classification
Jin et al (2004) employ a numerical grading of severity:[4]
- 0.5: intermittent thrombopenia
- 1.0: thrombopenia and small platelets
- 2.0: thrombopenia and normally responsive eczema or occasional upper respiratory tract infections.
- 2.5: thrombopenia and therapy-responsive but severe eczema or airway infections requiring antibiotics
- 3.0: both eczema and airway infections requiring antibiotics
- 4.0: eczema continuously requiring therapy and/or severe or life threatening infections
- 5.0: autoimmune disease or malignancy in an XLT/WAS patient.
Pathophysiology
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In Wiskott–Aldrich syndrome, the platelets are small and do not function properly. They are removed by the spleen, which leads to low platelet counts.
Wiskott–Aldrich syndrome was linked in 1994 to mutations in a gene on the short arm of the X chromosome, which was termed Wiskott-Aldrich syndrome protein (WASp). It was later discovered that the disease X-linked thrombocytopenia (XLT) was also due to WASp mutations, but different ones from those that cause full-blown Wiskott–Aldrich syndrome. Furthermore, the rare disorder X-linked neutropenia has been linked to particular mutations of the WASp gene.
The WASp gene codes for the protein by the same name, which is 502 amino acids long and is mainly expressed in hematopoietic cells (the cells in the bone marrow that develop into blood cells). The main function of WASp is to activate actin polymerization by binding to the Arp2/3 complex. In T-cell, WASp is important because it is known to be activated via T-cell receptor (TCR) signaling pathways to induce cortical actin cytoskeleton rearrangements that are responsible for forming the immunological synapse.
The immune deficiency is caused by decreased antibody production, and an inability for T cells to become polarized [5] (making it a combined immunodeficiency). This leads to increased susceptibility to infections, particularly of the ears and sinuses. T cells are unable to reorganize their actin cytoskeleton. The type of mutation to the WASp gene correlates significantly with the degree of severity: those that led to the production of a truncated protein caused significantly more symptoms than those with a missense mutation but a normal-length WASp. Although autoimmune disease and malignancy occur in both types of mutation, those patients with truncated WASp carry a higher risk.
A defect in CD43 molecule has been found to be associated in patients with Wiskott–Aldrich syndrome.[6]
Causes
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In Wiskott–Aldrich syndrome, the platelets are small and do not function properly. They are removed by the spleen, which leads to low platelet counts.
Wiskott–Aldrich syndrome was linked in 1994 to mutations in a gene on the short arm of the X chromosome, which was termed Wiskott-Aldrich syndrome protein (WASp). It was later discovered that the disease X-linked thrombocytopenia (XLT) was also due to WASp mutations, but different ones from those that cause full-blown Wiskott–Aldrich syndrome. Furthermore, the rare disorder X-linked neutropenia has been linked to particular mutations of the WASp gene.
The WASp gene codes for the protein by the same name, which is 502 amino acids long and is mainly expressed in hematopoietic cells (the cells in the bone marrow that develop into blood cells). The main function of WASp is to activate actin polymerization by binding to the Arp2/3 complex. In T-cell, WASp is important because it is known to be activated via T-cell receptor (TCR) signaling pathways to induce cortical actin cytoskeleton rearrangements that are responsible for forming the immunological synapse.
The immune deficiency is caused by decreased antibody production, and an inability for T cells to become polarized [5] (making it a combined immunodeficiency). This leads to increased susceptibility to infections, particularly of the ears and sinuses. T cells are unable to reorganize their actin cytoskeleton. The type of mutation to the WASp gene correlates significantly with the degree of severity: those that led to the production of a truncated protein caused significantly more symptoms than those with a missense mutation but a normal-length WASp. Although autoimmune disease and malignancy occur in both types of mutation, those patients with truncated WASp carry a higher risk.
A defect in CD43 molecule has been found to be associated in patients with Wiskott–Aldrich syndrome.[6]
Differentiating ((Page name)) from Other Diseases
Epidemiology and Demographics
The combined incidence of WAS and XLT is about 4-10 in 1 million live births. There is no geographical factor.
Risk Factors
Screening
Natural History, Complications, and Prognosis
Diagnosis
Diagnostic Study of Choice
History and Symptoms
In Wiskott-Aldrich syndrome, the platelets are small and do not function properly. They are removed by the spleen, which leads to low platelet counts. Splenomegaly is not an uncommon finding. Also, patients develop a type of itchy rash called eczema. Autoimmune disorders are also found in patients with WAS.
Physical Examination
Laboratory Findings
An elevated/reduced concentration of serum/blood/urinary/CSF/other [lab test] is diagnostic of [disease name].
OR
Laboratory findings consistent with the diagnosis of [disease name] include [abnormal test 1], [abnormal test 2], and [abnormal test 3].
OR
[Test] is usually normal among patients with [disease name].
OR
Some patients with [disease name] may have elevated/reduced concentration of [test], which is usually suggestive of [progression/complication].
OR
There are no diagnostic laboratory findings associated with [disease name].
Electrocardiogram
X-ray
Echocardiography or Ultrasound
CT scan
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Treatment of Wiskott-Aldrich syndrome is based on correcting symptoms. Aspirin and other non-steroidal anti-inflammatory drugs should be avoided, since these may interfere with platelet function. A protective helmet can protect children from bleeding into the brain which could result from head injuries. For severely low platelet counts, patients may require platelet transfusions or a splenectomy. For patients with frequent infections, intravenous immunoglobulins (IVIG) can be given to boost the immune system. Anemia from bleeding may require iron supplementation or blood transfusion.
Surgery
As Wiskott-Aldrich syndrome is primarily a disorder of the blood-forming tissues, a hematopoietic stem cell transplant, accomplished through a cord blood or bone marrow transplant offers the only hope of cure. This treatment is inherently fraught with risks, but is nonetheless recommended for patients with HLA-identical donors, matched sibling donors, or even in cases of incomplete matches if the patient is age 5 or under.
Primary Prevention
Secondary Prevention
Secondary preventive measures of wiskott aldrich syndrome are similar to primary prevention.
References
- ↑ Aldrich RA, Steinberg AG, Campbell DC (1954). "Pedigree demonstrating a sex-linked recessive condition characterized by draining ears, eczematoid dermatitis and bloody diarrhea". Pediatrics. 13 (2): 133–9. PMID 13133561.
- ↑ Wiskott, A (1937). "Familiärer, angeborener Morbus Werlhofii? ("Familial congenital Werlhof's disease?")". Montsschr Kinderheilkd. 68: 212–16.
- ↑ Binder V, Albert MH, Kabus M, Bertone M, Meindl A, Belohradsky BH (2006). "The genotype of the original Wiskott phenotype". N. Engl. J. Med. 355 (17): 1790–3. doi:10.1056/NEJMoa062520. PMID 17065640.
- ↑ Jin Y, Mazza C, Christie JR; et al. (2004). "Mutations of the Wiskott-Aldrich Syndrome Protein (WASP): hotspots, effect on transcription, and translation and phenotype/genotype correlation". Blood. 104 (13): 4010–9. doi:10.1182/blood-2003-05-1592. PMID 15284122.
- ↑ 5.0 5.1 "Wiskott-Aldrich Syndrome: Immunodeficiency Disorders: Merck Manual Professional". Retrieved 2008-03-01.
- ↑ 6.0 6.1 PMID 1683685 (PMID 1683685)
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