chairoij/ShutterStockImagine having your spleen removed, undergoing a double hip replacement, and receiving monthly blood transfusions to prevent severe pain attacks, all by the age of 13. That was the life of a teenager in France with sickle cell disease (SCD) until October 2014, when he received experimental gene therapy as part of a clinical study. Now, hes completely off all medications and his SCD is essentially gone, making him the hopeful poster child for the worlds first effective sickle cell disease therapy. (Dont these medical miracles that doctors cant explain.)

Standard treatments were not able to control his SCD symptoms [but] since receiving the stem cell transplant with LentiGlobin, he has been free from severe symptoms and has resumed normal activities, without the need for further transfusions, said study author Marina Cavazzana, MD, PhD, of Necker Hospital in Paris, France, where the trial was conducted, in a news release.

SCD is a inherited blood disorder where sufferers have sickle hemoglobin, an abnormal form of the oxygen-carrying protein which changes the shape of red blood cells (from a flexible disc shape to a rigid crescent one), making it hard for them to pass through blood vessels and often causing blockages that slow or stop the flow of oxygen-rich blood to nearby tissues, causing sudden and severe pain. Sickled red blood cells also die after 10 to 20 days, compared to normal ones which can live up to 120; this can cause the body to have trouble keeping up with red blood cell production, leading to anemia. A stem-cell transplant is currently the only curative option for patients, but fewer than 18 percent of patients are able to find a matching donor.

That is until now. The 13-year-old boy (known as Patient 1204) had bone marrow extracted, which was then genetically altered with the drug LentiGlobin BB305 so that his body made normal, healthy red blood cells instead of the sickle cells it was creating before. After just six months, the proportions of sickled red cells in his blood were significantly lower than those in untreated SCD patients. Now more than 15 months since the treatment, his body is still producing normal red blood cells and he hasnt experience any SCD-related episodes or hospitalizations, according to the study published in the New England Journal of Medicine.

Ive worked in gene therapy for a long time and we make small steps and know theres years more work. But here you have someone who has received gene therapy and has complete clinical remissionthats a huge step forward, Deborah Gill, PhD, of the gene medicine research group at the University of Oxford in England told BBC.

Scientists plan to test the drug on other sickle cell disease patients to see if the results are replicated.

MORE: This Grandmother Beat Cancer in a Groundbreaking 20-Minute Treatment

Read more:
Teen's Sickle Cell Disease 'Reversed' with Groundbreaking Therapy - Reader's Digest