# Wiskott-Aldrich Syndrome

Suspect Wiskott-Aldrich syndrome in boys with persistent microthrombocytopenia, eczema, infections, autoimmunity, or lymphoid malignancy; confirm the WAS variant and expedite curative therapy planning, because hematopoietic transplantation outcomes decline with older age and severe pretransplant infection.

**Clinical question:** How should physicians confirm Wiskott-Aldrich syndrome and select timely definitive therapy?

Updated: 2026-09-15T17:18:23.874101+00:00

## What matters in practice
- Persistent thrombocytopenia with small platelets in a male patient, particularly with eczema, recurrent infection, autoimmunity, or malignancy, should trigger evaluation for a WAS-related disorder rather than reflex attribution to immune thrombocytopenia. [3][15][16]
- Confirm the diagnosis with WAS gene sequencing; assessment of WAS protein expression helps phenotype severity and curative-treatment candidacy. [8][20]
- For severe disease or absent WAS protein, promptly refer for definitive cellular therapy; allogeneic hematopoietic stem cell transplantation is first-line when an HLA-compatible donor is available. [8][20]
- In a 308-patient transplant cohort, age 5 years or older, donor type, and pretransplant severe infection adversely affected survival; 5-year overall and event-free survival were 87.2% and 79.7%, respectively. [13]
- FDA-approved etuvetidigene autotemcel is an autologous gene-therapy option for patients aged 6 months or older with a pathogenic WAS mutation when HSCT is appropriate but no suitable HLA-matched related donor is available. [1]

## Recognize the phenotype and confirm a WAS-related disorder

Small platelets in an affected male are the key discriminator.

Evaluate a male patient with persistent thrombocytopenia for platelet size on peripheral smear and complete blood count indices before diagnosing isolated immune thrombocytopenia. The canonical WAS phenotype combines thrombocytopenia with small platelets, eczema, and immune deficiency; recurrent infections, autoimmunity, and lymphoreticular malignancy increase diagnostic concern. [1][3][10][15]

Order molecular testing of the WAS gene to establish the diagnosis. In patients being considered for curative therapy, assess WAS protein in peripheral-blood mononuclear cells by western blotting and flow cytometry; severe disease in a gene-therapy study was defined by clinical severity score 3-5 or absent WAS protein, with molecular confirmation by WAS sequencing. [8]

Do not exclude a WAS-related disorder solely because eczema or recurrent infections are not prominent. X-linked thrombocytopenia represents a milder phenotype, whereas absent or markedly reduced WAS protein and more severe clinical manifestations favor classic WAS and support early definitive-therapy planning. [6][11][20]
- Document bleeding phenotype, eczema burden, serious or recurrent infections, autoimmune manifestations, and prior or current lymphoid malignancy at the first specialty assessment; these features define severity and influence urgency of cellular-therapy evaluation. [1][4][11][20]
- Obtain a detailed family history of thrombocytopenia, bleeding, infections, or early male deaths compatible with X-linked inheritance, but proceed with WAS testing when the clinical phenotype is compelling regardless of family history. [3][10][11]

*Clinical patterns that should redirect chronic thrombocytopenia evaluation toward WAS-related disease. [3][6][10][15][17][20]*

| Finding | Interpretation | Next action |
| --- | --- | --- |
| Male patient with thrombocytopenia and small platelets | Characteristic laboratory pattern of classic WAS or X-linked thrombocytopenia. [3][15][16] | Order WAS gene sequencing and refer to clinical immunology and a cellular-therapy center. [8][20] |
| Thrombocytopenia plus eczema, recurrent infection, autoimmunity, or lymphoreticular malignancy | Favors classic WAS with combined immune dysregulation rather than isolated thrombocytopenia. [1][10][11] | Assess disease severity and WAS protein expression while beginning transplant or gene-therapy planning. [8][20] |
| Persistent thrombocytopenia with limited infections or eczema | Does not exclude a WAS-related disorder; milder X-linked thrombocytopenia can occur. [6][11][20] | Confirm the genotype and longitudinally assess for escalation to autoimmunity or malignancy. [11][20] |
| Macrothrombocytopenia | Atypical for the characteristic microthrombocytopenia of WAS and should broaden the inherited-thrombocytopenia differential. [15][17] | Reassess smear interpretation and pursue an alternative inherited-thrombocytopenia workup while considering WAS testing if other phenotype features remain persuasive. [15][17] |

## Control bleeding and infection risk while definitive therapy is arranged

Supportive management does not replace definitive correction of hematopoietic disease.

Treat active bleeding and clinically significant infection as immediate complications of a combined immunodeficiency with thrombocytopenia, while simultaneously expediting consultation with pediatric hematology, clinical immunology, and a transplant or gene-therapy program. WAS is life-threatening and carries susceptibility to bleeding, recurrent infection, autoimmunity, and lymphoreticular malignancy. [1][10]

Use the initial specialty assessment to identify conditions that worsen cellular-therapy risk: serious infection before hematopoietic cell transplantation was associated with worse overall and event-free survival in the PIDTC cohort. Infection control and stabilization should therefore proceed before conditioning when feasible, without allowing a prolonged workup to defer donor assessment or definitive-therapy referral. [13]

Avoid treating an apparent platelet-count response or dermatologic improvement as evidence that the underlying disorder has resolved. Gene-therapy studies measured improvement in eczema, infections, bleeding tendency, and autoimmunity, reflecting the multisystem disease burden that requires ongoing assessment beyond platelet count alone. [4][14]
- At baseline and before cellular therapy, record bleeding events, infection frequency and severity, eczema activity, autoimmune disease, and malignancy history; these outcomes are clinically relevant measures of disease control. [1][4][14]
- If lymphadenopathy, organ enlargement, unexplained constitutional symptoms, or other concern for lymphoreticular malignancy is present, coordinate urgent hematology-oncology evaluation because malignancy is a recognized WAS complication. [1][10][11]

*Management priorities before definitive cellular therapy. [1][4][13][14]*

| Clinical problem | Decision consequence | Action |
| --- | --- | --- |
| Active or prior serious infection | Pre-HCT severe infection is associated with poorer overall and event-free survival. [13] | Treat and stabilize infection promptly while advancing donor search and cellular-therapy consultation. [13] |
| Bleeding phenotype | Bleeding is a core disease manifestation and a treatment-response outcome. [1][4] | Coordinate hematology-directed bleeding management and track bleeding tendency longitudinally. [1][4] |
| Autoimmunity | Autoimmune disease may persist or flare despite cellular therapy; two patients with prior autoimmunity had post-gene-therapy flares. [14] | Document active and historical autoimmune disease before therapy and monitor after immune reconstitution. [14] |
| Eczema | Eczema is a core manifestation and a measurable response domain after gene therapy. [1][4] | Treat the skin disease while using eczema severity as one marker of systemic disease control. [4] |

## Choose allogeneic transplantation or autologous gene therapy

Donor availability, age, disease severity, and transplant risk drive selection.

Refer patients with severe WAS, particularly those with absent WAS protein, for definitive cellular therapy without delay. Allogeneic hematopoietic stem cell transplantation is regarded as first-line treatment when an HLA-compatible donor is available; outcomes are substantially better when treatment occurs before age 5 years in one reported cohort, with overall survival of 94% before age 5 years versus 66% at older ages. [8][20]

For patients aged 6 months or older with a WAS mutation in whom HSCT is appropriate but no suitable HLA-matched related donor is available, FDA-approved etuvetidigene autotemcel (Waskyra) provides an autologous genetically corrected hematopoietic stem-cell option. This strategy avoids the requirement for a matched related donor and avoids graft-versus-host disease associated with allogeneic transplantation. [1][14]

Do not restrict allogeneic HCT consideration to children solely on the basis of age. Adult patients may still be candidates when clinically indicated, but age at transplant, donor type, and prior serious infection are important adverse prognostic variables. [12][13]
- Start HLA donor assessment early in every patient with severe WAS being evaluated for allogeneic HCT. HLA-compatible donor availability is the principal branch point between standard allogeneic transplantation and the FDA-labeled gene-therapy population. [1][8]
- Discuss transplantation conditioning as a chimerism and toxicity tradeoff. Reduced-intensity regimens were associated with lower T-cell and myeloid donor chimerism in the PIDTC cohort, particularly with non-busulfan regimens. [13]
- Discuss gene therapy as a specialized cellular intervention rather than a nonmyeloablative alternative: reported lentiviral gene-therapy protocols used busulfan and fludarabine conditioning. [14]

### Allogeneic hematopoietic cell transplantation

Monitor lineage-specific donor chimerism and platelet recovery after HCT. Low myeloid donor chimerism was associated with lower platelet counts in the PIDTC cohort, and prior work links mixed chimerism to poor immune reconstitution and autoimmunity; myeloid donor engraftment below 50% was associated with persistent thrombocytopenia in a reported cohort. [8][13]

Counsel families that HCT can be effective but remains vulnerable to donor and conditioning effects. In 308 patients treated from 1990 through 2018, 5-year overall survival was 87.2% and event-free survival was 79.7%; older age, donor type, and pre-HCT severe infection negatively affected both outcomes. [13]
- A busulfan-based conditioning regimen was associated with higher post-HCT platelet counts in the PIDTC analysis. [13]
- Reduced-intensity conditioning may lower toxicity but carries a chimerism tradeoff that is particularly relevant when durable platelet correction is a treatment objective. [13]

### Autologous lentiviral gene therapy

Gene therapy uses autologous CD34-positive hematopoietic cells modified with a lentiviral vector expressing WAS complementary DNA, followed by conditioning and reinfusion. In a phase 1/2 study of five patients with severe WAS treated after busulfan-fludarabine conditioning, all were alive and well with sustained multilineage vector marking at a median 7.6 years of follow-up. [14]

Set expectations that immune and clinical improvement may exceed platelet correction. In that study, immune function improved despite subphysiologic transgenic WAS protein expression; higher vector copy number in the infused product was associated with more prominent platelet-count and myeloid cytoskeletal improvement. Prior autoimmunity remained clinically relevant because two patients experienced autoimmune flares after gene therapy. [14]
- The FDA indication requires a WAS mutation, age at least 6 months, appropriateness for HSCT, and absence of a suitable HLA-matched related stem-cell donor. [1]
- Use long-term follow-up to assess bleeding, infections, eczema, autoimmunity, platelet count, and multilineage hematopoietic correction. [4][14]

*Definitive-therapy selection and post-treatment surveillance considerations. [1][8][13][14][20]*

| Option | When to prioritize | Key tradeoff | Monitoring focus |
| --- | --- | --- | --- |
| Allogeneic HCT | Severe WAS with an HLA-compatible donor; early treatment is favored because outcomes decline with older age. [8][13][20] | Potential cure with donor-derived hematopoiesis, balanced against graft-versus-host disease, donor factors, conditioning toxicity, and mixed chimerism. [7][8][14] | Lineage-specific donor chimerism, platelet count, immune reconstitution, autoimmunity, graft-versus-host disease, and infection. [8][13] |
| Etu vetidigene autotemcel | Patient aged at least 6 months with a WAS mutation, appropriate for HSCT, and without a suitable HLA-matched related donor. [1] | Autologous approach avoids matched-related donor dependence and graft-versus-host disease but requires specialized manufacture, conditioning, and long-term follow-up. [1][14] | Bleeding, infections, eczema, autoimmunity, platelet count, immune function, and durable multilineage vector marking. [4][14] |

## Monitor disease activity and cellular-therapy durability by lineage and complication

Platelet count alone is insufficient to judge control.

At each longitudinal review, assess the domains that define ongoing WAS morbidity: bleeding tendency, eczema, frequency and severity of infections, autoimmunity, and malignancy. These were the principal clinical outcome domains in gene-therapy evaluation and remain appropriate targets after HCT or autologous therapy. [1][4][10][14]

After allogeneic HCT, interpret a falling platelet count in the context of donor myeloid chimerism rather than assuming isolated thrombocytopenia. Lower myeloid chimerism was associated with lower platelet counts, while reduced-intensity regimens were associated with lower T-cell and myeloid donor chimerism. [13]

After gene therapy, persistent or recurrent autoimmune disease requires active reassessment even if gene marking and WAS protein-expressing-cell proportions appear comparable to those in patients without autoimmunity. Autoimmune flares occurred in two patients with prior autoimmunity in a long-term phase 1/2 cohort. [14]
- Escalate evaluation for any new lymphadenopathy, systemic symptoms, or organ involvement because WAS confers increased susceptibility to lymphoreticular malignancy. [1][10][11]
- Use the patient’s pretherapy phenotype as the comparator: fewer serious infections, reduced bleeding tendency, improved eczema, and controlled autoimmunity are clinically meaningful measures of response. [4][14]

*Problem-oriented surveillance after definitive therapy. [1][4][8][13][14]*

| Domain | Concerning finding | Interpretation and next step |
| --- | --- | --- |
| Platelets | Suboptimal or declining platelet count after HCT | Assess donor myeloid chimerism; low myeloid chimerism is associated with lower platelet counts. [13] |
| Immune function | Recurrent or severe infections | Assess immune reconstitution and investigate infection promptly; infection burden is a core WAS outcome domain. [4][8][14] |
| Autoimmunity | New or recurrent autoimmune manifestations | Reassess disease activity even after gene therapy or HCT; prior autoimmunity may flare after gene therapy. [14] |
| Malignancy | Lymphadenopathy, constitutional symptoms, or other concern for lymphoid disease | Initiate hematology-oncology evaluation because lymphoreticular malignancy is a recognized WAS complication. [1][10] |

## References
1. FDA Approves First Gene Therapy Treatment for Wiskott-Aldrich Syndrome | FDA — www.fda.gov — https://www.fda.gov/news-events/press-announcements/fda-approves-first-gene-therapy-treatment-wiskott-aldrich-syndrome?display=full
2. FDA Approves First Gene Therapy Treatment for Wiskott-Aldrich ... — www.fda.gov — https://www.fda.gov/news-events/press-announcements/fda-approves-first-gene-therapy-treatment-wiskott-aldrich-syndrome
3. A novel mutation in Wiskott-Aldrich gene manifesting as ... — casereports.bmj.com — https://casereports.bmj.com/content/2018/bcr-2018-225123.full.pdf
4. Outcomes of Gene Therapy for Severe Wiskott-Aldrich Syndrome — jamanetwork.com — https://jamanetwork.com/journals/jama/fullarticle/2275447
5. Lentiviral haemopoietic stem/progenitor cell gene therapy for ... — www.thelancet.com — https://www.thelancet.com/journals/lanhae/article/PIIS2352-3026(19)30021-3/fulltext
6. Wiskott Aldrich syndrome: healthcare utilizations and disparities in transplant care | Scientific Reports — www.nature.com — https://www.nature.com/articles/s41598-021-84328-0
7. Hematopoietic Cell Transplantation in Wiskott-Aldrich Syndrome | Transplantation Immunology | Immunology | Health sciences | Topics | Nature Index — www.nature.com — https://www.nature.com/nature-index/topics/l4/hematopoietic-cell-transplantation-in-wiskott-aldrich-syndrome
8. Long-term safety and efficacy of lentiviral hematopoietic stem/progenitor cell gene therapy for Wiskott–Aldrich syndrome | Nature Medicine — www.nature.com — https://www.nature.com/articles/s41591-021-01641-x
9. Dupilumab successfully controlled eczema in Wiskott-Aldrich Syndrome over 52 weeks | Pediatric Research — www.nature.com — https://www.nature.com/articles/s41390-025-03941-1
10. Evidence for Long-term Efficacy and Safety of Gene Therapy for ... — www.cell.com — https://www.cell.com/molecular-therapy-family/molecular-therapy/pdf/S1525-0016(16)31813-5.pdf
11. How I treat Wiskott-Aldrich syndrome - ScienceDirect — www.sciencedirect.com — https://www.sciencedirect.com/science/article/abs/pii/S0006497125008638
12. Allogeneic hematopoietic stem cell transplantation outcome in oldest known surviving patients with Wiskott-Aldrich syndrome - ScienceDirect — www.sciencedirect.com — https://www.sciencedirect.com/science/article/pii/S2772829323001169
13. Hematopoietic Cell Transplantation for Wiskott-Aldrich syndrome: A PIDTC Report - ScienceDirect — www.sciencedirect.com — https://www.sciencedirect.com/science/article/pii/S2473952925007499
14. Outcomes of hematopoietic stem cell gene therapy for Wiskott-Aldrich syndrome - ScienceDirect — www.sciencedirect.com — https://www.sciencedirect.com/science/article/pii/S0006497123017287
15. Confirming or Excluding the Diagnosis of Wiskott-Aldrich Syndrome ... — journals.lww.com — https://journals.lww.com/jpho-online/fulltext/2004/07000/confirming_or_excluding_the_diagnosis_of.7.aspx
16. Misdiagnosis of Chronic Thrombocytopenia in Childhood - Ovid — journals.lww.com — https://journals.lww.com/jpho-online/fulltext/2003/07000/misdiagnosis_of_chronic_thrombocytopenia_in.10.aspx?Ppt=Article%7Cjpho-online%3A2003%3A07000%3A00010%7C%7C
17. Atypical Presentation of Wiskott–Aldrich Syndrome... - Ovid — journals.lww.com — https://journals.lww.com/ijru/fulltext/2021/16040/atypical_presentation_of_wiskott_aldrich_syndrome.19.aspx
18. EFI Abstracts - 2025 - HLA - Wiley Online Library — onlinelibrary.wiley.com — https://onlinelibrary.wiley.com/doi/full/10.1111/tan.70158
19. Abstracts for PBC Volume 69, Supplement 4 - Wiley Online Library — onlinelibrary.wiley.com — https://onlinelibrary.wiley.com/doi/full/10.1002/pbc.30099
20. Pediatric Blood & Cancer - Wiley Online Library — onlinelibrary.wiley.com — https://onlinelibrary.wiley.com/doi/pdf/10.1002/pbc.30099
21. Gene therapy for Whiskott–Aldrich syndrome: The latest news - Cavazzana - 2022 - Clinical and Translational Medicine - Wiley Online Library — onlinelibrary.wiley.com — https://onlinelibrary.wiley.com/doi/abs/10.1002/ctm2.815
22. Medicine® — journals.lww.com — https://journals.lww.com/md-journal/_layouts/15/oaks.journals/downloadpdf.aspx?an=00005792-202212160-00104
23. Eosinophilia Associated With Immune Deficiency — www.jaci-inpractice.org — https://www.jaci-inpractice.org/article/S2213-2198(22)00180-5/abstract
24. How I treat Wiskott-Aldrich syndrome | Blood | American Society of Hematology — ashpublications.org — https://ashpublications.org/blood/article-abstract/146/1/41/536678/How-I-treat-Wiskott-Aldrich-syndrome?redirectedFrom=fulltext

## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.