1. Copenhagen University Hospital Rigshospitalet, Denmark (A.A.R., H.B.).
2. New England Research Institutes, Watertown, MA (L.S.).
3. University of Michigan, Ann Arbor (S.M.D., M.R.).
4. Cleveland Clinic, OH (K.Z., H.L.).
5. Boston Children’s Hospital, MA (S.D.C., R.M.).
6. Yale University, New Haven, CT (E.K.H.).
7. Vanderbilt University Medical Center, Nashville, TN (J.B.).
8. Cincinnati Children’s Hospital Medical Center, OH (J.L.J.).
9. University of Chicago, IL (A.R.P.).
10. Northwestern University, Chicago, IL (L.C.).
11. Johns Hopkins University School of Medicine, Baltimore, MD (A.M.M.).
12. Washington University School of Medicine, St. Louis, MO (C.C., R.B.).
13. University of Colorado Anschutz Medical Campus, Aurora (M.T., L.M.).
14. Stanford University School of Medicine, Palo Alto, CA (M.T.W.).
15. Toronto Hospital for Sick Children, ON, Canada (L.B.).
16. University of Pennsylvania Perelman School of Medicine, Philadelphia (A.T.O.).
17. Children’s Hospital of Philadelphia, PA (J.R., K.Y.L.).
18. Ann & Robert H. Lurie Children’s Hospital of Chicago, IL (E.P.).
19. Heart Institute, University of São Paulo Medical School (Instituto do Coração), Brazil (A.C.P.).
20. Massachusetts General Hospital, Boston (G.D.L.).
21. MedStar Georgetown University Hospital, National Institutes of Health, Bethesda, MD (J.D.V.).
22. Brigham and Women’s Hospital, Boston, MA (A.L.C., C.A.M., S.D.S., E.J.O., E.B., C.Y.H.).
23. University of Glasgow, Glasgow, UK (J.J.V.M.).