hereditary elliptocytosis

Here’s a disorder that’s very similar to hereditary spherocytosis: hereditary elliptocytosis. Patients with this disorder have numerous elliptocytes (as the name says) rather than spherocytes – but many of the features of the two diseases are similar.

Hereditary elliptocytosis is a genetic disorder in which there are abnormalities of the red cell cytoskeleton. Most patients have abnormalities in spectrin, but a few have abnormalities in protein 4.1 (which attaches spectrin to actin) or glycophorin C (which attaches protein 4.1 to the cell membrane). Normal red cells are able to temporarily deform themselves from a biconcave disk into an elliptical shape as they squeeze through tiny capillaries. The red cells in hereditary elliptocytosis can do this too, but afterwards, their cytoskeletal defects prevent them from reverting to normal biconcave disk form, and they remain stuck in the elliptical shape. If you look at a blood smear from a patient with hereditary elliptocytosis, you’ll see a varying number of these elliptocytes (just under half of the red cells in the image above are elliptocytes). Another name commonly used for these cells is ovalocytes (although if you want to get picky, elliptocytes are thinner than ovalocytes).

Most patients with this disorder don’t even know they have it, because there are no symptoms to bring it to clinical attention. Some patients have a more severe disorder that resembles the anemia seen in hereditary spherocytosis: usually mild and well-compensated, with occasional crises. If the disease is particularly severe, splenectomy may be performed (the spleen is the site of destruction of the elliptocytes – so removing the spleen can alleviate symptoms). You wouldn’t just take out someone’s spleen without careful consideration, however, because asplenic patients have a very difficult time fighting off encapsulated bugs (like Streptococcus pneumoniae and Haemophilus influenzae).

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