Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 13-16: Hemoglobin C Disorders + Key Features Download Section PDF Listen +++ ++ Hemoglobin C is formed by a single amino acid substitution at the same site as in sickle hemoglobin (codon 6 of the beta globin gene) but with lysine instead of valine substituted for glutamate Hemoglobin C is nonsickling but may participate in polymer formation in association with hemoglobin S + Clinical Findings Download Section PDF Listen +++ ++ Homozygous hemoglobin C disease produces a mild hemolytic anemia with Splenomegaly Mild jaundice Pigment (calcium bilirubinate) gallstones Compared with patients who have homozygous SS disease, those with hemoglobin SC disease have Milder hemolytic anemia Milder clinical course Fewer vaso-occlusive events More retinopathy More priapism + Diagnosis Download Section PDF Listen +++ ++ Peripheral blood smear shows generalized red cell targeting and occasional cells with angular crystals of hemoglobin C Persons heterozygous for hemoglobin C are clinically normal Hemoglobin SC disease Hematocrit is usually 30–38%, with 5–10% reticulocytes, and compared to SS, fewer irreversibly sickled cells on the blood smear Target cells are more numerous than in SS disease Hemoglobin electrophoresis shows approximately 45–50% hemoglobin C, 50% hemoglobin S, and no increase in hemoglobin F levels + Treatment Download Section PDF Listen +++ ++ Folic acid 1 mg orally daily is advised; other treatment is usually necessary only for acute problems Splenectomy is occasionally required Cholecystectomy may be needed Laser eye surgery if retinal neovascularization occurs