Sickle cell S-C disease

Sickle cell S-C disease (also known as hemoglobin SC disease or HbSC disease) is a form of sickle cell disease in which an individual inherits one copy of the hemoglobin S (HbS) gene and one copy of the hemoglobin C (HbC) gene, both affecting the HBB (beta-globin) gene on chromosome 11. It is the second most common form of sickle cell disease after homozygous sickle cell anemia (HbSS). The abnormal hemoglobins cause red blood cells to become rigid and assume abnormal shapes, leading to vaso-occlusion, hemolytic anemia, and damage to multiple organ systems. Clinically, HbSC disease tends to be milder than HbSS disease on average, but it can still cause significant morbidity. Key features include moderate hemolytic anemia, episodic pain crises (vaso-occlusive crises), splenomegaly (the spleen often remains enlarged into adulthood, unlike in HbSS), and an increased risk of avascular necrosis of the femoral head. Patients with HbSC disease are particularly prone to proliferative retinopathy, which can lead to vision loss if untreated, and sensorineural hearing loss. Other complications include acute chest syndrome, stroke (though less frequently than in HbSS), priapism, and thromboembolic events. Pregnant women with HbSC disease face elevated risks of complications. Management of HbSC disease includes comprehensive supportive care, pain management during vaso-occlusive crises, folic acid supplementation, infection prevention with vaccinations and sometimes prophylactic antibiotics, and regular ophthalmologic screening for retinopathy. Hydroxyurea, a mainstay of HbSS treatment, may be used in HbSC disease for patients with frequent pain crises or severe complications, though evidence for its efficacy in this specific genotype is less robust. Blood transfusions may be required for severe anemia or acute complications. Hematopoietic stem cell transplantation remains the only established curative option and is considered in severe cases. Newborn screening programs in many countries now identify affected infants early, allowing for timely initiation of preventive care.

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