About HbSC Disease
HbSC disease is a compound heterozygous hemoglobinopathy caused by inheritance of one HbS allele (glutamic acid to valine substitution at position 6 of beta-globin) and one HbC allele (glutamic acid to lysine at the same position) in the HBB gene, producing a sickling disorder of intermediate severity between sickle cell trait and sickle cell disease. Red cells in HbSC disease have higher intracellular hemoglobin concentration than in HbSS disease, promoting polymerization of HbS and resulting in painful vaso-occlusive crises, organ damage, and retinopathy at rates distinct from classical sickle cell disease. Proliferative sickle cell retinopathy occurs at higher rates in HbSC disease than in HbSS disease and represents a significant complication requiring ophthalmologic surveillance.
Common Clinical Features
Clinical Trial Eligibility Tips
What to know before applying to HbSC Disease trials.
Hemoglobin electrophoresis or HPLC confirming HbSC genotype (approximately equal proportions of HbS and HbC, with no HbA) is required for enrollment; HbSC patients are sometimes enrolled in sickle cell disease trials but may be stratified separately from HbSS.
Baseline ophthalmologic assessment for proliferative retinopathy is particularly important in HbSC trials and should be documented; some trials require laser treatment of active retinopathy before enrollment.
Hydroxyurea use history, fetal hemoglobin percentage, and annual pain crisis rate over the prior 12 months are standard eligibility and stratification variables; patients on hydroxyurea may require stable dosing for 3-6 months before enrollment.
Patient Resources
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