Sickle cell disease affects millions of people worldwide and is caused by a genetic mutation that produces abnormal hemoglobin, which clumps together making sickle-, or half-moon-, shaped red blood cells. These red blood cells do not properly flow through the body and so get stuck in blood vessels, causing adverse symptoms in individuals with sickle cell disease. Patients are treated with blood transfusions to unblock vessels and prevent future blockages. The disease can also be treated with bone marrow transplants, but the odds of finding a matching donor are extremely low, around ten percent.
In France, a recent study using gene therapy was able to cure an individual, abolishing the symptoms associated with the disease as well as the biological markers that appear in blood work. Gene therapy involves using DNA in ways to compensate for already existing mutations and has proven effective in treating rare diseases.
This study used stem cells from the patient, meaning this type of treatment would be available to all and not rely on a matching donor. Researchers used lentiviral vector-mediated addition to insert a version of the beta-globin gene that would produce non-clumping hemoglobin into the stem cells.
In this successful case, stem cells were taken from a male patient at age 13, mutated using the above gene therapy technique, and then put back into his body. Within three months, he started to make normal hemoglobin. Two years later, the patient is completely symptom-free and does not need to take any medications. Further observations still need to be made since the individual is still producing abnormal hemoglobin because the mutated gene is still expressed in his DNA, thus he may still experience minor blockages.
If proven successful, this treatment would be limited to high-income countries because of the cost. However, this success provides hope for curing sickle cell disease in many individuals worldwide, as well as provides a model for the potential treatment of other common genetic disorders.