Cell Membrane

Question 1

Acanthocytosis/ Spur Cell Anemia

Answer 1

Defect: RBC cell membrane
Mode of Inheritance: Acquired
Mechanism: Haemolytic anemia caused by!excess cholesterol transferred to outer leaflet creates flat, scalloped cells with projections (spur cells), which increase SA of outer bilayer making cells less deformable; sequestration and destruction by spleen; associated with chronic liver disease (i.e. alcohol liver disease)
Characteristics: Ascites, jaundiced, caput medusa
Key Words: acanthocytes, cholesterol, chronic liver disease

Question 2

Hereditary Spherocytosis

Answer 2

Defect: RBC cytoskeletal membrane defect due to nonfunctional skeletal membrane protein; spectrin*, ankyrin, or protein 4.1
Mode of Inheritance: Autosomal dominant (75%)
Mechanism: Haemolytic anemia caused by!spectrin deficiency causing unstable membrane – loses membrane fragments and becomes less deformable resulting in sequestration and destruction by spleen
Characteristics: Splenomegaly, jaundice, gallstones
Key Words: spectrin, ankyrin, protein 4.1