Is Wiskott-Aldrich syndrome hereditary?

TL;DR: Wiskott-Aldrich syndrome is a hereditary, X-linked recessive genetic disorder caused by mutations in the WAS gene. Because it is X-linked, it primarily affects males, and mothers who are carriers have a 50% chance of passing the mutation to each son, while daughters have a 50% chance of being carriers.

Is Wiskott-Aldrich syndrome hereditary?

Wiskott-Aldrich syndrome is strictly a hereditary condition, meaning it is passed down through families via genetic material. It is classified as an X-linked recessive disorder. This means the mutation responsible for Wiskott-Aldrich syndrome is located on the X chromosome, one of the two sex chromosomes. Because males have only one X chromosome, a single copy of the mutated WAS gene is sufficient to cause the disease. In females, who have two X chromosomes, a healthy copy of the gene on the second X chromosome typically compensates for the mutation, which is why they are usually asymptomatic carriers rather than having the full expression of Wiskott-Aldrich syndrome.

How is Wiskott-Aldrich syndrome inherited?

The inheritance pattern for Wiskott-Aldrich syndrome follows the classic X-linked recessive model. The risk for family members is structured as follows:

• For sons of a carrier mother: Each son has a 50% chance of inheriting the mutated gene and developing Wiskott-Aldrich syndrome.


• For daughters of a carrier mother: Each daughter has a 50% chance of being a carrier of the mutation.


• For children of an affected male: All daughters will be obligate carriers of the mutation, while all sons will be unaffected, as the father passes his Y chromosome to his sons and his mutated X chromosome to his daughters.

Are de novo mutations common in Wiskott-Aldrich syndrome?

While Wiskott-Aldrich syndrome is typically inherited from a carrier mother, approximately 25% to 33% of cases are the result of a de novo (spontaneous) mutation. This means the mutation occurs for the first time in the affected individual and is not present in the mother’s genetic makeup. In these instances, the parents are not carriers, and the recurrence risk for future pregnancies is low, though it is never zero due to the possibility of germline mosaicism.

What is the role of genetic testing and counseling?

Genetic testing is the gold standard for confirming a diagnosis of Wiskott-Aldrich syndrome. Molecular genetic testing involves sequencing the WAS gene to identify pathogenic variants. Clinical geneticists strongly recommend genetic counseling for families with a history of the condition. Counseling helps parents understand the inheritance risks, explores options such as prenatal diagnosis via chorionic villus sampling (CVS) or amniocentesis, and discusses preimplantation genetic testing (PGT) for those planning future pregnancies. At DiseaseMaps.org, we recognize that navigating these decisions can be overwhelming, and genetic counselors provide the necessary context to make informed choices based on your specific family history.

Next steps

• Consult with a clinical geneticist to discuss molecular testing for the WAS gene.


• Request a referral for genetic counseling if you are planning a pregnancy and have a family history of immunodeficiency.


• Connect with the community at DiseaseMaps.org to share experiences with the 7 other members currently navigating life with Wiskott-Aldrich syndrome.


• Reach out to the Wiskott-Aldrich Foundation for disease-specific support and clinical trial information.

Medical disclaimer: This content is for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• National Institutes of Health (NIH) - Genetic and Rare Diseases Information Center (GARD): Wiskott-Aldrich syndrome.


• Online Mendelian Inheritance in Man (OMIM): Entry #301000 (Wiskott-Aldrich Syndrome).


• Orphanet: Wiskott-Aldrich syndrome (ORPHA:908).


• Immune Deficiency Foundation (IDF): Information on Wiskott-Aldrich Syndrome.