1. Institute of Stem Cell Biology and Regenerative Medicine, Stanford University, Palo Alto, California, USA
2. Department of Genetics, Stanford University School of Medicine, Palo Alto, California, USA
3. Department of Medicine, Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Palo Alto, California, USA
4. Departments of Internal Medicine, Biomedical Engineering, University of Iowa, Iowa City, Iowa, USA
5. Department of Surgery, Liver Transplantation Division, Stanford University School of Medicine, Palo Alto, California, USA
6. Veterans Administration Medical Center, Palo Alto, California, USA
7. Department of Statistics and Health Research and Policy, Stanford University, Palo Alto, California, USA