|MadSci Network: Cell Biology|
Sickle cell anemia is caused by a genetic mutation in the beta globin gene of hemoglobin. The most common mutation involves the substitution of the hydrophobic amino acid valine in place of hydrophilic glutamic acid at the sixth amino acid position of the protein. This substitution creates a hydrophobic spot on the outside of the protein structure that sticks to the hydrophobic region of an adjacent hemoglobin molecule's beta chain. This clumping together of the molecules into rigid fibers causes the "sickling" of red blood cells. There is no way to prevent the mutant hemoglobin from sticking together, since this is a chemical reaction. However, it could be possible to genetically engineer the hematopoetic stem cells to produce the non- mutant form of hemoglobin. This procedure would involve some sort of gene transfer followed by a transplant of the engineered cells back into the patient. In order to be effective, the old hematopoetic stem cells would have to be destroyed first, which would be a risky procedure, if the transplant did not take. In fact, a bone marrow transplant from a healthy patient would cure sickle cell anemia. However, the risks are deemed too severe to make this a standard medical procedure.
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