Liver biopsy will be the gold standard to assess fibrosis using Ishak score and morphometric evaluation of fibrosis. All children included will have a measure of liver stiffness using SWE with 5 measures performed in the area where the biopsy is performed and 5 measures in an other place in the liver. Fibrotest®/ Fibromax® will be performed on blood sample. All exams will be done within 1 month. diagnostic performance of SWE and Fibrotest®/ Fibromax® will be assessed respectively. algorithm using the results of both technics will be tested in order to test diagnostic performance and to obtain better performances.