European regulators have given the greenlight to Bluebird Bio’s Zynteglo, a gene therapy for a rare blood disorder.

Zynteglo (autologous CD34+ cells encoding BA-T87Q-globin gene) won the European Commission’s conditional marketing approval for patients 12 years and older who suffer from transfusion-dependent B-thalassemia, a rare form of anemia.

Patients with TDT must receive blood transfusions for life, which puts them at risk for organ failure because of iron overload. European regulators fast-tracked Zenteglo under its priority medicines program.

Bluebird won approval after handing up data from a Phase 1/2 trial that showed three of the four patients were able to go without a transfusion for at least year after receiving Zenteglo.