1. Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, 48109, USA
2. Current address: Ludwig Institute for Cancer Research, La Jolla, CA 92093-0653, USA
3. Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
4. Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI 48109, USA