Sickled Cells

Short answer: Sickle cell disease is a group of inherited red blood cell disorders caused by a mutation in the beta-globin gene, which helps make hemoglobin.

According to the US National Heart, Lung, and Blood Institute (NHLBI), normal red blood cells are disc-shaped and flexible, so they move easily through large and small vessels. The mutation swaps a single amino acid, valine for glutamic acid, producing hemoglobin S. When hemoglobin S gives up its oxygen in the tissues, it links into long, rigid strands inside the cell. A 2019 review in the Annual Review of Pathology by Prithu Sundd and colleagues describes how these polymers stiffen and distort the cell. The sickled cells are inflexible and can stick to vessel walls, slowing or blocking blood flow. That starves nearby tissue of oxygen and can cause sudden episodes of severe pain, called pain crises. NHLBI also notes that sickle cells break apart early, lasting only 10 to 20 days compared with 90 to 120 for normal red cells. The body may not keep up, which leads to anemia. Other complications NHLBI lists include acute chest syndrome, stroke, eye problems and infections. The disease is autosomal recessive: a person must inherit the mutation from both parents. The FDA says it affects about 100,000 people in the US. Chicago physician James B. Herrick first described it in the medical literature in 1910. On December 8, 2023, the FDA approved the first cell-based gene therapies for it, Casgevy and Lyfgenia, for patients 12 and older. The footage is a medical animation of red cells flowing through a vessel, then sickled cells clumping.

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