[1] Univ Oxford, John Radcliffe Hosp, Weatherall Inst Mol Med, Oxford OX3 9DS, England
[2] Univ Kelaniya, Dept Med, Kelaniya, Sri Lanka
[3] Lady Ridgeway Hosp Children, Colombo, Sri Lanka
[4] Gen Hosp, Natl Thalassaemia Ctr, Kurunegala, Sri Lanka
[5] Univ Hlth Network, Toronto, ON, Canada
[6] Childrens Hosp, Oakland, CA 94609 USA
[7] Univ Oxford, Weatherall Inst Mol Med, Oxford, England