The only treatment that can cure Wiskott Aldrich syndrome – WAS is a bone marrow or cord blood transplant (also called a BMT). A bone marrow or cord blood transplant replaces the abnormal cells in the bone marrow with healthy blood-forming cells from a family member or unrelated donor or cord blood unit. The healthy cells can come from the bone marrow or peripheral (circulating) blood of an adult donor or from the blood collected from the umbilical cord after a baby is born. The transplanted blood-forming cells will make normal platelets, T cells and B cells for the body.
The donor must closely match the patient’s tissue type. The best donor is usually a matched sibling. Each sibling has a 25% chance of being a match. However, since WAS is inherited, many children with WAS do not have a healthy matched sibling. For children without a suitable sibling donor, doctors may search the National Marrow Donor Program (NMDP) Registry for a suitable adult donor or cord blood unit. For boys age 5 and younger, transplants using unrelated donors have had similar outcomes to those using matched siblings.
If no suitable sibling or unrelated donor or cord blood unit is available, doctors may use one of the child’s parents or other family members as a donor. Each parent’s tissue type matches half of the child’s tissue type (a haploidentical match). For some inherited immune disorders, such as severe combined immunodeficiency (SCID), haploidentical donors have had good results. However, for boys age 5 and younger, the outcomes of haploidentical transplants have been much lower than those for transplants using matched siblings or unrelated donors.
Factors that Affect WAS Transplant Outcomes
A transplant can offer a cure to some boys with WAS, but it has serious risks and may not be a treatment option for all patients. A boy’s age at transplant affects his likelihood of survival. The likelihood of survival is highest in boys 5 years of age and younger. How closely the donor matches the patient is also an important factor in transplant outcomes.