A normal and abnormal red blood cell
Sickle cell anemia (also know as sickle cell disease) is a genetic blood disorder that causes red blood cells to form abnormally. The disease is more common in people of African or Mediterranean descent, and affects 3-5 million people across the globe, and about 100,000 Americans. 1 in every 500 African-American babies is born with the disease, and about 2 million Americans carry the sickle cell trait.
People who have sickle cell anemia don’t produce normal red blood cells, which are round and flexible and move around easily in the body. Instead, they make a mutant form of hemoglobin, the protein found in red blood cells, which results in fragile, abnormally-shaped cells that don’t carry as much oxygen or move around the body easily. These crescent, or sickle, shaped cells can get stuck in blood vessels or break up into little bits that impede regular blood flow. This causes tissue and organ damage and can cause strokes, lung problems and acute infections. Those with the disease can expect to live into their 50’s, but there is currently no cure.
But that may be set to change. Scientists have recently found a way to successfully correct sickle cell anemia in mice, and the treatment could potentially be applied to humans as well.
In sickle cell anemia, the problematic hemoglobin is not produced in utero, but only after birth. Fetuses use one gene to make hemoglobin while they are developing, and switch to a different gene after birth. It is this second, adult gene that is responsible for the problem hemoglobin and the disease.
In a study published in Science, a Harvard Medical School team identified the protein, BCL11A, responsible for making the switch from fetal to adult hemoglobin in mice. Once they blocked this protein in mice with sickle cell anemia, the mice went back to producing normal fetal hemoglobin and improved. Although the treatment is not currently applicable to humans, it is an exciting new development that hints at a potentially lasting treatment for those with the disease.