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  • Treatment: Previously splenectomy was considered routine in HS patients. Referral for splenectomy if clinically indicated can be made for patients with mild HS. The treatment of patients with mild to moderate HS and gallstones is also debatable, particularly since new treatments for cholelithiasis including laparoscopic cholecystectomy, endoscopic sphincterotomy, and extracorporal choletripsy, lower the risk of this complication. One approach is to splenectomize all patients with severe spherocytosis and all patients who suffer from significant signs or symptoms of anemia including growth failure, skeletal changes, leg ulcers, and extramedullary hematopoietic tumors.
  • Complications of HS include cholelithiasis and associated problems including biliary obstruction, cholecystitis and cholangitis. Hemolytic, aplastic, and megaloblastic crises may occur.

Hereditary elliptocytosis

  • Characterized by presence of elliptical cigar-shaped red blood cells

Hereditary spherocytosis

  • Assessment: Initial assessment of a patient with suspected HS should include a family history and questions about history of anemia, jaundice, gallstones and splenectomy. Physical examination should seek signs such as scleral icterus, jaundice, and splenomegaly. After diagnosing a patient with HS, family members should be examined for the presence of HS.
  • Clinical manifestations of the spherocytosis syndromes vary widely. “Typical” HS is marked by evidence of hemolysis with anemia, reticulocytosis, splenomegaly - older, jaundice, and gallstones, evidence of spherocytosis with spherocytes on peripheral smear and increased erythrocyte osmotic fragility, and a positive family history.
  • Lab findings: Typical HS patients have obvious spherocytes lacking central pallor on peripheral blood smear. Molecular studies have shown that specific morphologic findings are associated with certain membrane protein defects such as pincered erythrocytes (band 3), spherocytic acanthocytes (beta spectrin), or spherostomatocytes (protein 4.2). Most patients have mild to moderate anemia. Incubated osmotic fragility (OF) testing is considered the gold standard in diagnosing HS in a patient with Coombs-negative spherocytic hemolytic anemia. Other laboratory manifestations in HS are markers of ongoing hemolysis. Reticulocytosis, increased bilirubin, increased lactate dehydrogenase, increased urinary and fecal urobilinogen, and decreased haptoglobin reflect increased erythrocyte production or destruction.

Red Cell membrane Disorders

These include hereditary spherocytosis (HS), hereditary elliptocytosis (HE), hereditary pyropoikilocytosis (HPP), and the hereditary stomatocytosis (HSt) syndromes.

Peripheral blood smears in disorders of the erythrocyte membrane.

Hereditary Spherocytosis (HS)

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  • HS is characterized by the presence of spherical-shaped erythrocytes on the peripheral blood smear. It is the most common inherited anemia in individuals of northern European descent, affecting approximately 1 in 1000–2500 individuals. In approximately two thirds of HS patients, inheritance is autosomal dominant. In this group of “typical” HS patients, ankyrin mutations are the most common cause of HS, followed by mutations in band 3 and spectrin.
  • Pathophysiology of hereditary spherocytosis: The primary defect in hereditary spherocytosis is a deficiency of membrane surface area. Decreased surface area may produced by two different mechanisms: 1) Defects of spectrin, ankyrin, or protein 4.2 lead to reduced density of the membrane skeleton, destabilizing the overlying lipid bilayer and releasing band 3-containing microvesicles. 2) Defects of band 3 lead to band 3 deficiency and loss of its lipid-stabilizing effect. This results in the loss of band 3-free microvesicles. Both pathways result in membrane loss, decreased surface area, and formation of spherocytes with decreased deformability. These deformed erythrocytes become trapped in the hostile environment of the spleen where splenic conditioning inflicts further membrane damage, amplifying the cycle of membrane injury.

Gallagher P G Hematology 2005;2005:13-18

©2005 by American Society of Hematology

The erythrocyte membrane.

Gallagher P G Hematology 2005;2005:13-18

©2005 by American Society of Hematology

The erythrocyte membrane. A model depicting the major proteins of the erythrocyte membrane is shown: alpha and beta spectrin, ankyrin, band 3, 4.1 (protein 4.1), 4.2 (protein 4.2), actin, and GP (glycophorin).

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