School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, GA, USA.|Genome Informatics Section, Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.|Genome Informatics Section, Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.|Genome Informatics Section, Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.|School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, GA, USA.