First woman treated with CRISPR for Sickle Cell Disease treatment is showing good recovery after 17 months of treatment.
Victoria gray, 34, from USA becomes the first woman to show promising results of gene editing technology CRISPR to be used in treatment of rare genetic disorders.
People born with sickle cell disease have mutations in their two copies of a gene for hemoglobin, the oxygen-carrying protein in red blood cells. The altered proteins stiffen normally flexible red blood cells into a sickle like shape. The cells can clog blood vessels, triggering severe pain and raising the risk of organ damage and strokes.
They engineered CRISPR’s DNA-cutting enzyme and “guide RNA” to home in on and break the BCL11A gene. Investigators have tinkered with genes to counter the malfunctioning hemoglobin. They remove a patient’s blood stem cells and, in the lab, disable a genetic switch called BCL11A that, early in life, shuts off the gene for a fetal form of hemoglobin. The patient then receives chemotherapy to wipe out their diseased cells, and the altered stem cells are infused. With the fetal gene now active, the fetal protein restores missing hemoglobin in thalassemia. In sickle cell disease it replaces some of the flawed adult hemoglobin, and also blocks any remaining from forming sticky polymers.
Others who treat these diseases say it’s too early to crown a specific genetic treatment the winner. For example, reversing the fetal hemoglobin off switch, as the new CRISPR and RNA-based gene therapy strategies do, allows blood cells to make natural levels of the protein. But so far there are no signs that Bluebird’s treatment results in excess adult hemoglobin that causes problems, Williams says. And although a virus-carrying gene can land in the wrong place and trigger cancer, CRISPR could similarly make harmful off-target edits. There is no sign of that so far. Still, “We need long-term follow-up” for all the strategies, says the National Institutes of Health’s (NIH’s) John Tisdale, a coleader of the Bluebird study.
In spite of all the problems or uncertainties, the treatment gives a hope to the scientific community yo develop a cheaper and reliable treatment for millions of people suffering from Sickle Cell disease or Thalassemia.
