In these patients, hypersplenism might account for thrombocytopenia; however, the other 78% of patients with baseline thrombocytopenia did not have splenomegaly; other causes such as decreased level or activity of TPO, autoimmune reaction to platelets, and direct infection of platelets and megakaryocytes by HCV might contribute to the thrombocytopenia. This evidence concerns the gene TPO and Thrombocytopenia.