1. Feinberg School of Medicine Northwestern University Chicago IL U.S.A.
2. School of Medicine University of Pennsylvania Perelman Philadelphia PA U.S.A.
3. National Jewish Health Denver CO U.S.A.
4. School of Medicine University of Colorado Denver CO U.S.A.
5. NYU Winthrop Hospital Mineola NY U.S.A.
6. Nationwide Children's Hospital The Ohio State University College of Medicine Columbus OH U.S.A.
7. Children's Hospital Los Angeles Keck School of Medicine University of Southern California Los Angeles CA U.S.A.
8. Oregon Health & Science University Portland OR U.S.A.