Wiskott-Aldrich syndrome (WAS) is an inherited disorder characterized by a deficient immune system and significantly reduced number of platelets in the blood, which are used to help blood to clot. Typically platelet levels are reduced from birth, which often leads to mucosal bleeding and bloody diarrhea in affected infants, along with easy bruising and prolonged bleeding after trauma. Because of the immune system deficiency, affected males are susceptible to recurrent bacterial and viral infections which could lead to life-threatening complications. They are also at risk for autoimmune disorders and most will have mild to severe eczema. Affected individuals are also at increased risk for developing certain types of cancer. Survival rates have increased over the years as treatments have improved, however, without bone marrow transplantation, life expectancy is only into the early teens. Bone marrow transplant is the only known cure for WAS. WAS is caused by pathogenic variants in the WAS gene.