Department of Biostatistics and Bioinformatics, Center for Bioinformatics and Computational Biology, Institute for Genome Sciences and Policy, Duke University, Durham, North Carolina 27708, USA. tomfohr@duke.edu|Department of Biostatistics and Bioinformatics, Center for Bioinformatics and Computational Biology, Institute for Genome Sciences and Policy, Duke University, Durham, North Carolina 27708, USA. tomfohr@duke.edu|Department of Biostatistics and Bioinformatics, Center for Bioinformatics and Computational Biology, Institute for Genome Sciences and Policy, Duke University, Durham, North Carolina 27708, USA. tomfohr@duke.edu