1. Department of Paediatrics; Sickle Cell Disease Research Centre; College of Medicine; King Saud University; Riyadh Saudi Arabia
2. King Fahad Hospital; Hofuf Saudi Arabia
3. Department of Biostatistics; Boston University School of Public Health; Boston MA USA
4. College of Pharmacy; King Saud University; Riyadh Saudi Arabia
5. Al-Omran Scientific Chair; College of Medicine; King Faisal University; Al-Ahsa Saudi Arabia
6. Department of Medicine; Centre of Excellence in Sickle Cell Disease; Boston University School of Medicine; Boston MA USA