Diagnosis:
Sickle cell trait
• Sickle cell trait (heterozygous hemoglobin S) is caused by a β-globin mutation β6Glu->Val . In the homozygous state, hemoglobin polymerization leads to red cell sickling, which can cause vasoocclusive crises. However, in the heterozygous state, clinical symptoms are very rare.
• Sickle cell trait is generally considered a benign disorder both hematologically (normal complete blood count) and clinically.
• Sickle cell trait on hemoglobin electrophoresis is characterized by the identification of one band in the A-position and one band in the S-position on both alkaline cellulose acetate and acid electrophoresis. It can also be readily identified on cation exchange high-performance liquid chromatography (HPLC), isoelectric focusing, and capillary zone electrophoresis. The sickle solubility test is positive.
• Sickle cell trait is diagnosed by identifying the presence of hemoglobin A and hemoglobin S using two independent tests. In addition, hemoglobin A must be greater than hemoglobin S (usually 35% to 45% of total hemoglobin).
• The peripheral blood smear and complete blood cell count (CBC) are usually completely normal in sickle cell trait. However, microcytosis and target cells may occasionally be seen. Sickle cells are generally not present.
