1. The Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, and University of Lisbon; Lisbon Portugal
2. The Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine; Philadelphia
3. The Children's Hospital of Philadelphia; Philadelphia Pennsylvania
4. The Children's Hospital of Philadelphia and Temple University; Philadelphia Pennsylvania
5. Hospital of the University of Pennsylvania; Philadelphia
6. Johns Hopkins University School of Medicine; Baltimore Maryland