Brian Madeux sits with his girlfriend Marcie Humphrey at a hospital California. AP

OAKLAND, California - Scientists have for the first time tried editing a gene inside the body in an attempt to permanently change a person's DNA to try to cure a disease.

The experiment was done on Monday in California on 44-year-old Brian Madeux. Through an IV, he received billions of copies of a corrective gene and a genetic tool to cut his DNA in a precise spot.

"It's kind of humbling" to be the first to test this, said Madeux, who has a metabolic disease called Hunter syndrome. "I'm willing to take that risk. Hopefully it will help me and other people."

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 major boost to the fledgling field of gene therapy. Scientists have edited people's genes before, altering cells in the lab that are then returned to patients. There also are gene therapies that don't involve editing DNA.

But these methods can only be used for a few types of diseases. Some give results that may not last. Others supply a new gene like a spare part, but can't control where it inserts in the DNA, possibly causing a new problem like cancer.

This time, the gene tinkering is happening in a precise way. It's like sending a mini surgeon along to place the new gene in exactly the right location.

"We cut your DNA, open it up, insert a gene, stitch it back up. Invisible mending," said Doctor Sandy Macrae, president of Sangamo Therapeutics, the company testing this for two metabolic diseases and hemophilia. "It becomes part of your DNA and is there for the rest of your life."

Associated Press