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Hemolytic Anemia Associated with Red Cell Membrane Defects
Published in Harold R. Schumacher, William A. Rock, Sanford A. Stass, Handbook of Hematologic Pathology, 2019
A multitude of mutations that cause HE have been identified in several different genes that encode proteins of the erythrocyte membrane skeleton (Fig. 1). The most common mutations causing HE are found in genes for α and β spectrin. These mutations, found mostly in blacks, produce spectrin dimers with defective ability to self-associate into tetramers. Deficient or dysfunctional protein 4.1 is produced by another group of HE mutations. Glycophorin C deficiency, the result of several different mutations, can also give rise to HE. SAO is the consequence of a mutation in band 3.
Inherited Disorders of Red Cell Membrane Proteins
Published in Ronald L. Nagel, Genetically Abnormal Red Cells, 2019
In some patients with HE(4.1 + ), protein 4.9 is also missing.85,86 The exact function of protein 4.9 in the red cell membrane is unclear, but its behavior suggests that it serves as an actin-bundling protein.87 Clinically, these patients have an atypical hereditary elliptocytosis, with spherocytes and increased osmotic fragility. In family members with homozygous disease and complete lack of protein 4.1, HE(4.10), the hemolysis is quite severe. Deficiency of glycophorin C has also been reported in the context of protein 4.1 and 4.9 deficiencies.88 The function of this protein is also poorly understood, but may play a role in providing an attachment site for protein 4.1.89
A novel EPB41 p.Trp704* mutation in a Korean patient with hereditary elliptocytosis: a case report
Published in Hematology, 2020
Soyoung Shin, Kyung-Ah Hwang, Kyuhyun Paik, Joonhong Park
HE occurs in 0.3–0.5 per 1000 newborns, and patients are asymptomatic in about 90% of cases [9]. Approximately 95% of patients with HE have a mutation in genes responsible for α- and β-spectrin expression, i.e. polypeptides which in tetrameric form compose the basis of the cell cytoskeleton [6]. Mutations associated with the protein 4.1 and glycophorin C are rare [6]. Patients with a mutation on only one allele are asymptomatic, while in cases when it is bilateral suffer moderate or more severe hemolytic anemia [6,9]. In addition, the hereditary nature of the disorder is also supported by the absence of elements indicating other conditions that are associated with the presence of elliptocytes, such as deficiencies in iron, folic acid, or vitamin B12 [9].
Targeting Loxosceles spider Sphingomyelinase D with small-molecule inhibitors as a potential therapeutic approach for loxoscelism
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Priscila Hess Lopes, Mário T. Murakami, Fernanda C. V. Portaro, Kerly Fernanda Mesquita Pasqualoto, Carmen van den Berg, Denise V. Tambourgi
SMases D binding to erythrocytes is an important event in the mechanism of haemolysis. Cleavage of the external portions of the glycophorins by autologous cell membrane proteases, activated after SMase D binding, allows complement activation and lysis10. The three selected compounds significantly reduced the binding of the SMases D present in the whole venom to the erythrocytes membrane, the compound 5 being the most efficient inhibitor (Figure 3A). Analysis of the glycophorin C (GPC) expression on the erythrocyte surface showed that compounds 1 and 5 completely prevented the GPC cleavage induced by L. laeta venom (Figure 3B), while compound 6 showed a partial inhibition of GPC cleavage.