The Genome Center at Washington University, St. Louis, Missouri 63108, USA. dkoboldt@genome.wustl.edu|The Genome Center at Washington University, St. Louis, Missouri 63108, USA. dkoboldt@genome.wustl.edu|The Genome Center at Washington University, St. Louis, Missouri 63108, USA. dkoboldt@genome.wustl.edu|The Genome Center at Washington University, St. Louis, Missouri 63108, USA. dkoboldt@genome.wustl.edu