RecruitingNCT04416178
Blood
HbSC Disease
Also known as sickle cell HbSC, hemoglobin SC disease, compound heterozygous sickle cell
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 HB
Gene HBB (HbS+HbC)Prevalence Estimated 1 in 833 African American births in the United States; prevalence varies significantly by ancestryOnset Infancy; typically identified on newborn screeningAutosomal recessive (compound heterozygous)
1
studies recruiting now
as of 7 Sept 2026
37
studies registered in total
as of 7 Sept 2026
1
countries with a recruiting site
as of 7 Sept 2026
4 Jun 2020
most recent study posted
among recruiting studies
Recruiting trials
Showing the 1 most recently updated recruiting study, as recorded 7 Sept 2026. Live status on each study page.
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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
Vaso-occlusive pain crises of moderate severityProliferative sickle cell retinopathy with risk of vision lossMild to moderate hemolytic anemia with higher hemoglobin than HbSSSplenomegaly persisting into adulthood (unlike HbSS where autoinfarction occurs)Splenic sequestration crisesAvascular necrosis of femoral and humeral headsAcute chest syndromePregnancy-related complications including increased fetal loss
From Orphanet’s phenotype annotations (CC BY 4.0). Not a complete list.
Before you apply
Things trial teams commonly ask about for HbSC Disease. Not eligibility rules; those are set by each study.
- 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.
Related conditions
Information, not medical advice. Trial listings are shown as recorded on ClinicalTrials.gov; whether any study is right for you is a decision for you and your clinicians, and eligibility is decided by each research team. Disease information from Orphanet (CC BY 4.0).