Hereditary red cell membrane defects: diagnostic and clinical aspects.

The plasma membrane of the erythrocyte accounts for all of this cell’s antigenic, transport, and mechanical characteristics, particularly its ability to undergo large passive deformations during repeated passage through the narrow capillaries of the microvasculature, throughout its 120-day life span. The determinant of normal membrane cohesion is the system of “vertical” linkages between the phospholipid bilayer and membrane skeleton, formed by the interactions of the cytoplasmic domains of various membrane proteins with the spectrin-based skeletal network. Band 3 and Rh-associated glycoprotein (RhAG) provide such links by interacting with ankyrin, which in turn binds to β-spectrin. Protein 4.2 binds to both band 3 and ankyrin and can regulate the avidity of the interaction between band 3 and ankyrin. Glycophorin C, band 3, XK, Rh, and Duffy all bind to protein 4.1R, the third member of the ternary junctional complex with β-spectrin and actin1–2. Red cell membrane disorders are inherited diseases due to mutations in various membrane or skeletal proteins, resulting in decreased red cell deformability, reduced life span and premature removal of the erythrocytes from the circulation. The red cell membrane disorders include hereditary spherocytosis, hereditary elliptocytosis, hereditary ovalocytosis and hereditary stomatocytosis.