Victoria Gray is the first person in the US with a genetic disorder to get treated with the revolutionary gene-editing technique called CRISPR. Now, a year on from her experimental treatment for sickle cell disease, the results are looking promising, as NPR reports.

The billions of genetically modified cells doctors infused into Gray’s body clearly appear to be alleviating virtually all the complications of her disorder. The results looked good a couple of months after treatment, but doctors were wary about guaranteeing long-term results. Now that 12 months have passed with continued improvement, they are more optimistic about sustained success.

Sickle cell disease is caused by a genetic mutation that produces a defective form of hemoglobin, a protein needed by red blood cells to nourish the body with oxygen. It causes intense pain and often premature death. The experimental CRISPR treatment involves removing cells from patients’ bone marrow and using CRISPR to edit a gene, which enables the cells to produce a protein known as fetal hemoglobin. Scientists had hoped that at least 20 percent of the hemoglobin in Gray’s system would be fetal hemoglobin, but the results are far better with almost 50 percent fetal hemoglobin cells. 

Most importantly, Gray’s health has been greatly improved. She hasn’t had any severe pain attacks since the treatment and hasn’t required any emergency room treatments, hospitalizations, or blood transfusions. Two other patients in the world have received the same treatment for similar disorders and are also doing well. 

Sickle cell disease is the most commonly inherited blood disorder in the US, affecting 70,000 to 80,000 Americans. It predominantly affects African Americans at a rate of about 1 in 500. Developing an effective treatment method for the disease would be a huge leap forward for the medical community and this promising treatment is a significant step towards a widely available treatment.