Wiskott-Aldrich syndrome (WAS)

Nearly every child with WAS starts showing signs before turning 1. The quickest first test is a blood count that checks both the number and the size of platelets. In WAS, platelets are few and unusually small, even in a newborn’s cord blood.

Doctors then check whether blood cells make the WAS protein (WASp). They may also test how well the child makes antibodies after certain vaccines, which is often poor in WAS. A genetic test that finds a change in the WAS gene confirms the diagnosis. Knowing the family’s gene change also makes it possible to find female relatives who carry it and to test in a later pregnancy.

Newborn screening for SCID is not designed to find WAS. In one study of stored newborn blood spots from 11 children with WAS, only 4 had markedly low levels of the markers these screens look for.

Supportive care treats the problems while a longer-term plan is made. It can include immunoglobulin (antibody) replacement to prevent infections, preventive antibiotics for some people, thick moisturizers and steroid ointments for eczema, and platelet transfusions for active bleeding rather than on a routine schedule. Live vaccines such as MMR, chickenpox and rotavirus are not given. Removing the spleen can raise platelet counts but greatly raises the risk of severe infection.

A donor stem cell transplant can correct both the platelet and the immune problems. In a large study of 308 people at US and Canadian centers, people did better when the transplant happened before age 5 and before any severe infection, and donor type also affected results. Matched brothers, matched unrelated donors, cord blood and half-matched (haploidentical) family donors are all used.

Waskyra (etuvetidigene autotemcel) adds a working WAS gene to the patient’s own blood-forming stem cells. The FDA approved it on December 9, 2025, and the European Union on January 9, 2026. In both places it is for patients 6 months and older with a WAS gene change for whom a stem cell transplant is appropriate but who have no suitable HLA-matched related donor. It still requires collecting the patient’s cells, the antibody medicine rituximab and reduced-intensity conditioning chemotherapy. Because the gene is delivered by a modified virus, the US label warns of a lifelong risk that the treatment could cause cancer and calls for checks for blood cancer every year for at least 15 years.

Decades ago, WAS was thought to be fatal in early childhood. Today the outlook is far better, thanks to better supportive care, donor transplants and, more recently, gene therapy. Boston Children’s Hospital says a child whose blood and immune systems are restored should be able to enjoy an active adult life, including having a family.

Age at treatment matters a great deal. In a large study at North American transplant centers, people transplanted before age 5 were more likely to survive than those transplanted later. Without a lasting treatment, WAS remains a serious disease. The Immune Deficiency Foundation estimates that 15% to 20% of people with WAS eventually develop cancer.

Long-term results are also improving. In an Italian registry, an estimated 75% of people with WAS were alive 25 years after a transplant. For transplants done after 2000, the figure rose above 80%.