[1] Brown Univ Hlth, Comprehens Sickle Cell Ctr, Providence, RI USA
[2] Brown Univ, Brown Univ Hlth, Alpert Med Sch, Providence, RI USA
[3] Brown Univ, Dept Pediat, Alpert Med Sch, Providence, RI USA
[4] Yale Sch Med, Dept Med, Sect Hematol, New Haven, CT 06510 USA