Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; Department de Biologia Cellular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Cerdanyola, Spain. Electronic address: marta_venturas@fas.harvard.edu. Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts. Nuffield Department of Women's and Reproductive Health, John Radcliffe Hospital, Oxford University, Oxford, United Kingdom. Nuffield Department of Women's and Reproductive Health, John Radcliffe Hospital, Oxford University, Oxford, United Kingdom; Juno Genetics, Oxford Science Park, Oxford, United Kingdom. Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Department of Obstetrics and Gynecology and Reproductive Medicine, Hospital Foch, Suresnes, France. Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; Center for Computational Biology, Flatiron Institute, New York, New York.