Just seven years after scientists announced the first use of Crispr-Cas9 gene editing technology on human cells, researchers shared new evidence this week that Crispr can be used to cure two serious genetic disorders.

On Tuesday, NPR reported that a patient in Nashville had seen a dramatic decline in her symptoms of sickle cell disease after receiving a single gene therapy treatment in July. Sickle cell, which can lead to inflammation, debilitating pain, and life-threatening circulatory problems, affects millions of people around the world.

That same day, the biotech companies behind the sickle-cell treatment, Crispr Therapeutics and Vertex, also shared promising results from their first attempt to cure a case of beta thalassemia, another genetic disorder that affects blood proteins. Nine months after receiving the experimental treatment, a patient in Germany with beta thalassemia has almost no signs of the disorder.

Promising preliminary data from one of the first human trials testing the safety and efficacy of a CRISPR gene therapy has just been revealed. Although it is too early to evaluate long-term effects, the initial reports are impressively successful for two patients with severe genetic blood diseases.

Until February of this year, when pharmaceutical companies CRISPR Therapeutics and Vertex began a large global trial into a treatment called CTX001, no human outside of China had been officially treated with a CRISPR-based gene editing therapy.

CTX001 was developed to treat two types of inherited blood disease, beta-thalassemia and sickle cell disease. Both conditions are caused by a mutation in a single gene and the treatment involves engineering a patient’s stem cells with a single genetic change designed to raise levels of fetal hemoglobin in red blood cells.