Wiskott-Aldrich syndrome (WAS) is a rare X-linked recessive disease characterized by eczema, thrombocytopenia (low platelet count), immune deficiency, and bloody diarrhea (secondary to the thrombocytopenia). It is also sometimes called the eczema-thrombocytopenia-immunodeficiency syndrome in keeping with Aldrich's original description in 1954. It is caused by a defective gene on the X-chromosome that affects the production of platelets and antibodies. The disease is usually confirmed with tests for immunoglobulin levels, which are unusually low.