Dept. of Genetics, 300 Pasteur Drive, Stanford University Medical School, Stanford, CA 94305-5120, USA. rees@genome.stanford.edu <rees@genome.stanford.edu>|Dept. of Genetics, 300 Pasteur Drive, Stanford University Medical School, Stanford, CA 94305-5120, USA. rees@genome.stanford.edu <rees@genome.stanford.edu>|Dept. of Genetics, 300 Pasteur Drive, Stanford University Medical School, Stanford, CA 94305-5120, USA. rees@genome.stanford.edu <rees@genome.stanford.edu>|Dept. of Genetics, 300 Pasteur Drive, Stanford University Medical School, Stanford, CA 94305-5120, USA. rees@genome.stanford.edu <rees@genome.stanford.edu>|Dept. of Genetics, 300 Pasteur Drive, Stanford University Medical School, Stanford, CA 94305-5120, USA. rees@genome.stanford.edu <rees@genome.stanford.edu>