OAKLAND, Calif. (AP) — Scientists for the first time have tried gene editing inside the body in a bold attempt to permanently change a person's DNA to try to cure a disease.

The experiment was done Monday in Oakland, California, on 44-year-old Brian Madeux (muh-DOE). Through an IV, he received billions of copies of a corrective gene for a rare metabolic disease and a genetic tool to precisely cut his DNA and allow the gene to slip in.

Signs of whether it's working may come in a month; tests will show for sure in three months.

If it's successful, it could give a safer, more precise and permanent way to do gene therapy. The treatment is made by Sangamo Therapeutics, which plans to test it for other diseases including hemophilia, a blood clotting disorder.