Broad Institute of MIT and Harvard, Cambridge, Mass; Center for Microbiome Informatics and Therapeutics, Massachusetts Institute of Technology, Cambridge, Mass; Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark. Department of Dermatology and Allergology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland. Broad Institute of MIT and Harvard, Cambridge, Mass; Center for Microbiome Informatics and Therapeutics, Massachusetts Institute of Technology, Cambridge, Mass. Institute of Clinical Chemistry and Laboratory Medicine, University Hospital Regensburg, Regensburg, Germany. Institute of Functional Genomics, University of Regensburg, Regensburg, Germany. Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, Mass. Department of Dermatology and Allergology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland. Electronic address: Annamari.Ranki@hus.fi. Broad Institute of MIT and Harvard, Cambridge, Mass; Center for Microbiome Informatics and Therapeutics, Massachusetts Institute of Technology, Cambridge, Mass; Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, Mass; Center for Computational and Integrative Biology and Department of Molecular Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Mass. Electronic address: xavier@molbio.mgh.harvard.edu.