Wiskott-Aldrich syndrome (WAS) covers a group of rare serious disorders affecting about four people in a million and usually affects only males. WAS affects the function of white blood cells, making those affected susceptible to serious infections. There is also a significant reduction in the size and number of platelets (microthrombocytopenia), causing those affected to bleed easily.
WAS is caused by mutations or defects in the WAS gene that gives the instruction to make the WAS protein. The WAS gene defect and the severity of the condition varies widely between individuals. Severe cases may be present soon after birth or develop in the first year of life. Four clinical forms have been identified. Classic WAS is the most severe form of WAS. Its main symptoms are repeated bouts of infection, prolonged and severe bleeding leading to bruising easily, severe eczema and a higher incidence of leukaemia and lymphoma, and autoimmune disorders.
Milder forms of WAS are X-linked thrombocytopenia, a condition with low platelet numbers but without many of the other symptoms of WAS, and X-linked neutropenia, a condition with low amounts of white blood cells known as neutrophils but with normal levels of the WAS protein. The mildest form is called intermittent thrombocytopenia where the platelet abnormalities are sporadic and there is no immunodeficiency.
There have been enormous advances in the care of people with WAS due to improved control of infection, transfusion services and stem cell transplantation (e.g. bone marrow transplant), with those successfully transplanted leading relatively normal lives. Antibiotics are used to prevent and treat infections, and immunoglobulin replacement therapy is used to manage the condition. Platelet and red blood cell infusions can be used to treat excessive bleeding. Moisturising and steroid creams are used to treat eczema. Stem cell transplantation by a bone marrow or cord blood transplant offers the chance of a cure and is successful in 9 out of 10 cases. Gene therapy is also being developed as a potential alternative for people unable to find a suitably matched donor.