7 United States sites
12 to 54 Years
1. Participant must have sickle cell anemia (hemoglobin SS) or sickle Beta-zero (null)
thalassemia (hemoglobin S-B0) as confirmed at the local institution by hemoglobin
analysis after six months of age.
2. Participant must be 9 to 48 months of age. All screening procedures except MRI can be
completed between 9 and 12 months of age, with the exception of the MRI, for which the
child must have reached the age of 12 months.
3. Informed consent must be signed by the participant’s legally authorized guardian
acknowledging written consent to join the study.
1. History of a focal neurologic event lasting more than 24 hours with medical
documentation or a history of prior overt stroke.
2. Other neurological problems, such as neurofibromatosis, lead poisoning, non-febrile
seizure disorder, or tuberous sclerosis.
3. Known human immunodeficiency virus (HIV) infection.
4. Treatment with anti-sickling drugs or hydroxyurea within 3 months or anticipated
treatment during the course of the study.
5. Chronic blood transfusion therapy, ongoing or planned.
6. Poor adherence likely per his/her hematologist and study coordinator based on previous
compliance in clinic appointments and following advice.
7. Presence or planned permanent (or semi-permanent) metallic structures attached to
their body. (e.g., braces on teeth), which their physicians believe will interfere
with the MRI of the brain.
8. History of two or more TCD studies with a velocity ≥ 200 cm/sec by the non-imaging
technique, or ≥185 cm/sec for the imaging technique or a indeterminate TCD.
9. Significant cytopenias [absolute neutrophil count (ANC) <1500/ul, platelets
<150,000/ul, reticulocytes <80,000/ul, unless the hemoglobin is > 9 g/dl]. Cytopenias
will be considered transient exclusions.
10. Other significant organ system dysfunction
11. Known allergy or intolerance of hydroxyurea
12. Significant prematurity (gestational age of < 32 weeks)