Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, Pacific Northwest National Laboratory, Richland, WA 99352, USA Max Planck Institute of Biochemistry and Evotec AG 82152, Martinsried, Germany and Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, Pacific Northwest National Laboratory, Richland, WA 99352, USA Max Planck Institute of Biochemistry and Evotec AG 82152, Martinsried, Germany and Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.