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Health

Scientists Tried to Edit Genes Inside Someone’s Body for the First Time

Doctors hope the treatment will change this man's DNA and cure his metabolic disease.
Associated Press/YouTube

Brian Madeux is 44 years old. He's one of the oldest people with a metabolic disease called Hunter syndrome, a condition that affects about one in 100,000 people, almost exclusively men. It’s caused by a missing gene that tells the liver to make an enzyme to break down certain carbohydrates. The carbs that accumulate in cells without the enzyme disrupt the body’s normal functioning; Madeux has had 26 operations, for ear, eye, and gallbladder problems, for bones pinching his spinal column, and for hernias and bunions. Weekly infusions of the enzyme can ease some symptoms, but can't prevent brain damage.

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The Associated Press reports that he’s now become the first human patient that scientists have tried to edit the genes of inside their body. On Monday in Oakland, California, doctors attached Madeux to an IV that fed billions of copies of a corrective gene into his body in hopes it will change his DNA and cure his condition. “It’s kind of humbling” to be the first test case, he told the AP. “I’m willing to take that risk. Hopefully it will help me and other people.” Less than 10,000 people worldwide have metabolic diseases like Hunter syndrome, which is incurable, because many die when they're very young.

Along with the corrective gene, the IV solution Madeux received contains a gene-editing tool called zinc finger nucleases. (Another editing tool you may have heard of is CRISPR.) Two zinc finger proteins act as molecular scissors, designed to target a specific section of DNA. The fingers and the corrective gene are carried through the bloodstream via a modified virus until they reach the liver. Cells there produce the corrective gene, and the zinc fingers snip the DNA, letting the new gene slip in. The altered gene directs the cell to produce the enzyme lacking in patients with Hunter syndrome.

“We cut your DNA, open it up, insert a gene, stitch it back up. Invisible mending,” Dr. Sandy Macrae, president of Sangamo Therapeutics, a California company testing it for two metabolic diseases and hemophilia, told the AP. “It becomes part of your DNA and is there for the rest of your life.”

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In Madeux’s case, only 1 percent of his liver cells must be altered to successfully treat the disease, according to his physician, Dr. Paul Harmatz, who’s leading the study. Doctors won’t know for three months if the procedure was successful, but they may see signs of it working in about a month. The goal is to try the treatment on up to 30 adults to test its safety before eventually treating children with Hunter syndrome when they’re young before damage occurs. There are risks: In 1999, one patient died when the virus used to carry the corrective gene and gene-editing tools provoked an immune response; newer studies use a different virus that’s proven much safer.

Tinkering with genes can also have unforeseen circumstances, as when patients whose genes were corrected for an immune disorder developed leukemia because a cancer gene was inadvertently activated. The precision of gene editing is supposed to minimize the potential for unexpected results: You put the gene exactly where you want it.

A final concern is that the modified virus carrying the gene payload wouldn’t stay in the liver. It could reach sperm or eggs, where the genetic modifications could be passed on to future generations. But doctors say they’ve accounted for that worry, and included safeguards that prevent the treatment from working outside the liver.

For Madeux, the first person to actually undergo this kind of treatment, those questions may be academic. He’s looking for positive results. “I’m nervous and excited,” Madeux told the AP. “I’ve been waiting for this my whole life, something that can potentially cure me.”

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