The first clinical trial of CRISPR-Cas9 sponsored by U.S. companies has launched, testing the genome-editing technique in patients with the blood disorder beta thalassemia, according to an announcement posted Friday on the U.S. clinical trials website.

The Phase 1/2 clinical trial, co-sponsored by Vertex Pharmaceuticals and using an experimental treatment from CRISPR Therapeutics, will be conducted at a single hospital in Regensburg, Germany, and aims to recruit up to 12 adults with the inherited disease. Although it was only a matter of time before the start of the first company-sponsored CRISPR clinical trial, Editas Medicine’s experimental treatment for a rare form of blindness was widely expected to be the first in the clinic.