Wiskott Aldrich Syndrome

What is Wiskott-Aldrich syndrome?

Wiskott-Aldrich syndrome is a rare genetic immunodeficiency that keeps a child's immune system from functioning properly. It also makes it difficult for a child's bone marrow to produce platelets, making a child prone to bleeding. It occurs mostly in males. According the National Institutes of Health, only 1 to 10 out of every 1 million boys has Wiskott-Aldrich syndrome.

The human immune system constantly patrols, protects and defends the body from all types of “enemies,” including bacteria, viruses and parasites. The blood and immune system arises from a developing fetus’ bone marrow. Bone marrow stem cells eventually mature into all of the different blood cells, including platelets that control bleeding, and two immune cell types that play the important roles in warding off infection: T cells (white blood cells that identify and attack perceived “invaders”) and B cells (white blood cells that produce antibodies against infection). In addition, stem cells give rise to other types of white blood cells that also play important roles in clearing infections.

When a child has Wiskott-Aldrich syndrome:

  • the T cells and B cells are there but don’t work right
  • the white blood cells do not properly reach the sites of infections

Without normal immune cells, a child with Wiskott-Aldrich syndrome is at constant risk for:

  • pneumonia
  • eczema (atopic dermatitis)
  • chronic, bloody diarrhea
  • ear and sinus infections
  • viral infections like herpes, cytomegalovirus (CMV) and Epstein-Barr virus (EBV)
  • many other types of infection

These problems are further complicated by the other aspect of Wiskott-Aldrich syndrome: The child’s body does not properly produce platelets, the clotting agents that stop bleeding from getting out of control. The platelets that are produced are small and are only produced in small numbers. Without healthy platelets, the child is likely to experience frequent and hard-to-control bleeding, even from the mildest bumps and scrapes. This bleeding can occur:

  • under the skin
  • from the nose
  • from the gums and mouth
  • in bowel movements
  • in the brain

As a result of these combined deficiencies, children with Wiskott-Aldrich syndrome are also at elevated risk for developing:

There is more than one kind of Wiskott-Aldrich syndrome. The majority of boys have the type known as the “classic” form, though some experience a milder form of the disease known as X-linked thrombocytopenia (XLT). This is caused by a defect in the same gene involved in classic Wiskott-Aldrich syndrome, but the symptoms are much milder.

Usually, children with X-linked thrombocytopenia have platelets that are overly small in both size and number. As a result, they have trouble with easy bleeding and bruising, but do not experience the other, more severe complications.

However, it is often difficult to predict whether a male baby born with a mutation in the Wiskott-Aldrich syndrome gene will develop the severe form of the disease or its milder variant, XLT. Moreover, also patients with XLT can progress to develop typical complications of Wiskott-Aldrich syndrome as they become older. Therefore, it is important that both patients with Wiskott-Aldrich syndrome and those with XLT be followed regularly by their doctor and by specialists in this disease.

How we care for Wiskott-Aldrich syndrome

Boston Children’s has a long history of caring for children with complex disorders of the blood and immune system. Clinicians in Dana-Farber/Boston Children's Cancer and Blood Disorder Center and our Division of Allergy and Immunology are regarded as international leaders in understanding and treating rare conditions like Wiskott-Aldrich syndrome.

The only known cure for Wiskott-Aldrich syndrome is a stem cell transplant (using as bone marrow, peripheral blood or umbilical cord blood from a healthy suitably tissue matched donor). Once introduced into your child's bloodstream, the stem cells can develop into normal immune cells and platelets. The Stem Cell Transplant Center at Dana-Farber/Boston Children’s – one of the first and most renowned pediatric transplant centers in the nation – performs over 90 stem cell transplants each year. Our specialists not only conduct groundbreaking stem cell research and devise exciting new treatments; they also have a unique understanding of the special needs of the youngest, smallest patients.

In addition, Dana-Farber/Boston Children's has opened one of the first gene therapy clinical trials for children with WAS in the world and the only one in the United States. The clinical trial for Wiskott-Aldrich syndrome — which transplants genetically modified stem cells from a child's own bone marrow or blood cells — may signify a promising new approach to fighting and defeating the disease.