Normal red blood cells are round, almost like doughnuts. They move through small blood vessels in the body to deliver oxygen, which is carried by a substance called hemoglobin. In sickle cell disease, one little change in the hemoglobin can cause it to form long rods when it gives away oxygen. These rigid rods change the round red cells into hard, sticky sickle shapes. When these hard and pointed red cells go through the small blood tube, they clog the flow and break apart. This can cause pain, damage and a low blood count, or anemia.
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