Since moving to Oklahoma, he has focused his research on understanding acquired and hereditary thrombotic thrombocytopenic purpura (TTP), beginning the Oklahoma TTP Registry in 1991. Throughout his career he has published 231 original research articles and 146 invited articles/editorials. In 1996 he was the principal author for the first clinical practice guideline developed by the American Society of Hematology (ASH), focused on immune thrombocytopenia. He has continued to be active in ASH. In 2002, he was the editor of the 1st edition of the ASH Self-Assessment Program, which has been updated annually. In 2003, he developed the Clinical Research Training Institute, which has become a popular annual program. In 2005, he served as ASH president. In 2012, he received the ASH Wallace H. Coulter Award for Lifetime Achievement in Hematology. Research Interests: Epidemiology and long-term outcomes of platelet disorders The Oklahoma Thrombotic Thrombocytopenic Purpura (TTP) Registry Drug-induced thrombocytopenia Gestational thrombocytopenia