Variant Hemoglobins Of Note

Hemoglobin S-Beta Thalassemia

This combination hemoglobin may produce a clinical picture as severe as sickle cell anemia, with virtually no

Figure 8.8 Hemoglobin SC. Note the presence of crystals with pointed projections.

hemoglobin A present. The anemia will be microcytic hypochromic, showing the influence of the thalassemia gene, with nRBCs, target cells, polychromasia, and sickle cells. The RDW will be increased as well as the reticulocyte count. As opposed to the usual presentation of sickle cell anemia, splenomegaly is usually present. The severity of the condition overall depends on the beta thalassemia genotype inherited; patients inheriting B0 have a more severe presentation. On alkaline electrophoresis, two bands are present, one at the location of hemoglobin S and one at the location of hemoglobin A2.

Hemoglobin E

This abnormal hemoglobin has an extremely high occurrence in individuals from southeast Asian countries. Individuals may inherit the hemoglobin either heterozygously and homozygously. Surprisingly, the homozygous conditions of this abnormal hemoglobin presents no clinical complications. Individuals show a marked microcytic hypochromic picture, with some target cells and slight polychromasia, but are asymptomatic. On alkaline electrophoresis, there is a strong band located in the same position as hemoglobin C , while the heterozygous condition shows 70% hemoglobin A and 30% hemoglobin E. Hemoglobin E is the second most common hemoglobin variant worldwide and is being seen with increasing frequency due to large numbers of southeast Asians emigrating to North America (Fig. 8.9).

Worldwide US

Figure 8.8 Hemoglobin SC. Note the presence of crystals with pointed projections.

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