1. Department of Computer Science, University of California Irvine , Irvine , CA 92697 , USA
2. Institute for Genomics and Bioinformatics, University of California , Irvine CA 92697 , USA
3. Department of Computer Science and Engineering, University of South Carolina , Columbia , SC 29208 , USA
4. Department of Biological Chemistry, Center for Epigenetics and Metabolism, School of Medicine, University of California , Irvine , CA 92697 , USA