###Human: Please provide some information about factor V Leiden. ###Assistant: Hello, Welcome to the icliniq.com.  At this moment I am giving you further information regarding your daughter condition. She has factor V Leiden mutation, which is a congenital cause of thrombosis. So Xarelto (Rivaroxaban) like good anticoagulant drug prescribed to her should be continued. AST (aspartate aminotransferase ) normal range is usually up to 40 in most of the laboratory. Her AST levels are not alarmingly raised. Sometimes the mild viral temporary infection can lead to high AST. If it is raised much than further workup needed otherwise not. Repeat AST after few days. I hope the provided information will help you. Get back with more query whenever required.