Gene-editing recently saved the lives of two baby girls who had an incurable form of leukemia. Now, the same type of process has been used to cancel out all the symptoms of a French teenager’s sickle cell disease.

Sickle cell disease is one that mainly affects people of African, Caribbean, Middle Eastern, Eastern Mediterranean, and Asian origin. Around 275,000 babies are born with it every single year.

The afflicted have unusually shaped (sickle) blood cells thanks to a coding error in the gene for hemoglobin, the oxygen-carrying segment of red blood cells. This means that the blood cells can’t flow effortlessly around the body, and sometimes get trapped in various valves.

The consequences of this life-long condition are complex and varied, but most commonly the patient suffers from bouts of severe anemia due to the inefficient transport of oxygen. They are also at a higher risk of contracting major infections, and can suffer from occasional, extremely painful paroxysms known as sickle cell crises. Stunted growth and strokes are also symptoms in some cases.

Conventional medicine cannot cure it. The only way to potentially cure it to date has been to use bone marrow or stem cell transplants from a healthy donor, which would allow the patient’s body to produce healthy blood cells. This does work, but the risk of a dangerous immune response – where the transplanted cells begin attacking the patient’s normal cells – is often too high.

However, as reported by a study in the New England Journal of Medicine, a teenager was brought to Necker Children’s Hospital in Paris back in 2014 for a game-changing therapy. A specific gene, one that's able to induce an “anti-sickling” effect on red blood cells, was inserted into the patient’s own stem cells using a modified virus.

The cells were then allowed to transform into red blood cells, which then began to proliferate around the patient’s body. Fifteen months later, the boy, now 15, is not suffering from any of the effects of sickle cell disease. It appears that at least 50 percent of his blood cells have normal hemoglobin and are normally shaped.

^{Sickle cells in among normal blood cells. Dr Graham Beards/Wikimedia Commons; CC BY-SA 3.0}

Although this isn’t a cure for the disease, this treatment has proven so effective that the symptoms have been quashed, and he is off all other forms of medication and treatment.

The gene therapy was concocted by scientists at Bluebird Bio based out of Cambridge, Massachusetts. They’ve treated six other patients with sickle cell disease in the same way, and although the results have yet to be published, it appears that it has not worked as successfully in all of them just yet.

However, trials are still taking place, and the future is looking increasingly bright for those with this unfortunate condition.

[H/T: Associated Press]