Abnormalities of the erythrocyte membrane

Abstract

Primary abnormalities of the erythrocyte membrane are characterized by clinical, laboratory, and genetic heterogeneity. Among this group, hereditary spherocytosis patients are more likely to experience symptomatic anemia. Treatment of hereditary spherocytosis with splenectomy is curative in most patients. Growing recognition of the long-term risks of splenectomy has led to re-evaluation of the role of splenectomy. Management guidelines acknowledge these considerations and recommend discussion between health care providers, patient, and family. The hereditary elliptocytosis syndromes are the most common primary disorders of erythrocyte membrane proteins. However, most elliptocytosis patients are asymptomatic and do not require therapy.

Keywords: Anemia; Erythrocyte membrane; Hereditary elliptocytosis; Hereditary pyropoikilocytosis; Hereditary spherocytosis; Splenectomy.

Figure 1. The Erythrocyte Membrane

A model of the major proteins of the erythrocyte membrane is shown: α- and β-spectrin, ankyrin, band 3 (the anion exchanger), 4.1 (protein 4.1) and 4.2 (protein 4.2), actin and glycophorin. From Perrotta S, Gallagher PG, Mohandas N. Hereditary spherocytosis. Lancet 2008;372:1411-1426; with permission.

Figure 2. Peripheral Blood Smears in Hereditary Spherocytosis

A. Typical hereditary spherocytosis. Characteristic spherocytes lacking central pallor are seen. B. Severe, recessively-inherited spherocytosis. Numerous small, dense spherocytes and bizarre erythrocyte morphology with anisocytosis and poikilocytosis associated with severe hemolysis are seen.

Figure 3. Testing in Hereditary Spherocytosis

A. Eosin-5-maleimide (EMA) binding. Histogram of fluorescence of EMA-labeled erythrocytes from a normal control and a patient with typical hereditary spherocytosis. Decreased fluorescence in observed from HS erythrocytes. B. Osmotic fragility curves in hereditary spherocytosis. The shaded region is the normal range. Results representative of both typical and severe spherocytosis are shown. A tail, representing fragile erythrocytes conditioned by the spleen, is common in spherocytosis patients prior to splenectomy.

Figure 4. Peripheral Blood Smears in Hereditary Elliptocytosis

A. Hereditary elliptocytosis. Smooth, cigar-shaped elliptocytes are seen. B. Hereditary pyropoikilocytosis. Pronounced microcytosis, poikilocytosis, fragmentation of erythrocytes and elliptocytes are seen.