1. Department of Genetics, Center for Genetics and Genomics, Brigham and Women's Hospital, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
2. Gastrointestinal Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
3. Immune Disease Institute and Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA.
4. Center for Computational and Integrative Biology, Harvard Medical School, Boston, MA 02114, USA.
5. Dana-Farber Cancer Institute, Division of AIDS, Harvard Medical School, Boston, MA 02115, USA.