Sickle cell anemia is among the most common inherited diseases in the world. Despite its cause having been understood by scientists for six decades, a treatment has not yet become available. Finally, researchers are expecting that trials will begin next year on new gene therapy techniques.
Sickle cell anemia causes deformed red blood cells, which can lead to anemia, pain, tissue damage, organ failure, and even heart attacks and strokes. In sickle cell anemia, these blood cells take on a crescent shape, like a sickle, instead of their normal, more rounded shape. These deformed cells break apart easily, causing anemia. The damaged cells collect on the walls of blood vessels, blocking blood flow. This can result in severe pain.
In the western world, with the help of blood transfusions and other treatments, sickle cell patients can live into their 40s. In Africa, patients tend to die during childhood.
The condition is caused by a genetic fault that alters one of the amino acids that comprises hemoglobin, the main element of red blood cells. This leads to the deformed shape of the red blood cells. The condition is carried by parents who are symptom-free. When two of these carriers have children, there is a one-in-four chance the offspring will inherent sickle cell genes from both parents, and develop sickle cell anemia. It is thought to have originated in Africa and other parts of the world as a defense against malaria. 300 children with sickle cell are born every year.
In some individuals who inherit the disease, their bodies continue producing foetal hemoglobin throughout their lives, instead of switching to adult hemoglobin, which is what occurs for most people. This foetal hemoglobin seems to protect the body against the disease.
“Those individuals are supplied with foetal h2emoglobin throughout their lives and for those who also inherit sickle cell anemia this protects them against the disease by making a substance that can carry oxygen round the bodies,” said professor Stuart Orkin of Harvard Medical School. “We have calculated that you only need to make a small amount of foetal hemoglobin to halt sickle’s symptoms.”
Earlier research found that a gene called BCL11A stops the production of foetal hemoglobin after birth.
According to Orkin, “What we aim to do is to stop it doing this. We want to suppress the suppressor and allow foetal hemoglobin to continue to be made in the body. We can now use gene-editing technologies to cut out that little enhancer so that the BCL11A gene stops shutting down foetal hemoglobin production and allow children with sickle cell disease to start making it in their blood.”
Orkin says trials are expected to begin in the near future.