Chapter 15 Red Blood Cell Membrane Disorders

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Figure 15-1 A SIMPLIFIED CROSS-SECTION OF THE ERYTHROCYTE MEMBRANE.

The lipid bilayer forms the equator of the cross-section with its polar heads (small circles) turned outward. 4.1R, Protein 4.1R; 4.2, protein 4.2; Rh, Rhesus polypeptide; RhAG, Rh-associated glycoprotein; LW, Landsteiner-Wiener glycoprotein.

(From Perrotta S, Gallagher PG, Mohandas N: Hereditary spherocytosis. Lancet 372:1411, 2008.)

Table 15-1 Erythrocyte Membrane Abnormalities in Hereditary Spherocytosis, Hereditary Elliptocytosis, and Related Disorders

Gene Disorder Comment
α-Spectrin HS, HE, HPP, NIHF Location of mutation determines clinical phenotype. α-Spectrin mutations are most common cause of typical HE.
Ankyrin HS Most common cause of typical dominant HS.
Band 3 HS, SAO, NIHF In HS “pincer-like” spherocytes on smear presplenectomy. SAO erythrocytes have transverse ridge or longitudinal slit.
β-Spectrin HS, HE, HPP, NIHF Location of mutation determines clinical phenotype. In HS, acanthrocytic spherocytes on smear presplenectomy.
Protein 4.2 HS Common in Japanese HS.
Protein 4.1 HE
Glycophorin C HE Concomitant protein 4.1 deficiency is basis of HE in glycophorin C defects.

HE, Hereditary elliptocytosis; HPP, hereditary pyropoikilocytosis; HS, hereditary spherocytosis; NIHF, nonimmune hydrops fetalis; SAO, Southeast Asian ovalocytosis.

Table 15-2 Peripheral Blood Film Evaluation in a Patient With Red Cell Membrane Disorder

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Shape Pathobiology Diagnosis
Microspherocytes Loss of membrane lipids leading to a reduction of surface area resulting from deficiencies of spectrin, ankyrin, or band 3 and protein 4.2

Removal of membrane material from antibody-coated red cells by macrophages

Removal of membrane-associated Heinz bodies, with the adjacent membrane lipids, by the spleen

HS

Immunohemolytic anemias

Heinz body hemolytic anemias

Elliptocytes Permanent red cell deformation resulting from a weakening of skeletal protein interactions (such as the spectrin dimer-dimer contact). This facilitates disruption of existing protein contacts during shear stress–induced elliptical deformation. Subsequently, new protein contacts are formed that stabilize elliptical shape

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