Wiskott Aldrich Syndrome is an X-linked disease characterized by immunodeficiency, eczema and thrombocytopenia; a milder form of the disease known as X-Linked thrombocytopenia also exists. The thrombocytopenia in both WAS and XLT is characterized by: severe thrombocytopenia with platelet counts frequently less than 10-30,000/ul; small platelets which may be dysfunctional; and, as a result, a high rate of serious bleeding including intracranial hemorrhage.