1. From the Dana–Farber/Boston Children’s Cancer and Blood Disorders Center and Harvard Medical School, Boston (R.F.G.), and Agios Pharmaceuticals, Cambridge (A.J.B., S.B., L.H., C.K., P.H., M.-H.J., C.B.) — all in Massachusetts; Hôpital Saint Vincent de Paul, Lille (C.R.), and Unité des Maladies Génétiques du Globule Rouge, Centre Hospitalier Universitaire Henri Mondor, Créteil (F.G.) — both in France; Hammersmith Hospital, Imperial College Healthcare NHS Trust, London (D.M.L.); Fondazione IRCCS Ca’ Granda...