Sun.Star Cebu

Scientists try gene editing

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Scientists, for the first time, have tried editing a gene inside the body in a bold attempt to permanentl­y change a person’s DNA to cure a disease.

The experiment was done 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. Some 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 inside the body. 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 Dr. Sandy Macrae, president of Sangamo Therapeuti­cs, the California company testing this for two metabolic diseases and hemophilia. “It becomes part of your DNA and is there for the rest of your life.” That also means there’s no going back, no way to erase any mistakes the editing might cause.

“You’re really toying with Mother Nature” and the risks can’t be fully known, but the studies should move forward because these are incurable diseases, said one independen­t expert, Dr. Eric Topol of the Scripps Translatio­nal Science Institute in San Diego.

Protection­s are in place to help ensure safety, and animal tests were very encouragin­g, said Dr. Howard Kaufman, a Boston scientist on the National Institutes of Health panel that approved the studies.

He said gene editing’s promise is too great to ignore. “So far there’s been no evidence that this is going to be dangerous,” he said. “Now is not the time to get scared.”

Fewer than 10,000 people worldwide have these metabolic diseases, partly because many die very young. Those with Madeux’s condition, Hunter syndrome, lack a gene that makes an enzyme that breaks down certain carbohydra­tes. These build up in cells and cause havoc throughout the body.

Patients may have frequent colds and ear infections, distorted facial features, hearing loss, heart problems, breathing trouble, skin and eye problems, bone and joint flaws, bowel issues and brain and thinking problems.

“Many are in wheelchair­s ... dependent on their parents until they die,” said Dr. Chester Whitley, a University of Minnesota genetics expert who plans to enroll patients in the studies.

Safety issues plagued some earlier gene therapies. One worry is that the virus might provoke an immune system attack. In 1999, 18-year-old Jesse Gelsinger died in a gene therapy study from that problem, but the new studies use a different virus that’s proved much safer in other experiment­s.

Another worry is that inserting a new gene might have unforeseen effects on other genes. That happened years ago, when researcher­s used gene therapy to cure some cases of the immune system disorder called “bubble boy” disease. Several patients later developed leukemia because the new gene inserted into a place in the native DNA where it unintentio­nally activated a cancer gene.

“When you stick a chunk of DNA in randomly, sometimes it works well, sometimes it does nothing and sometimes it causes harm,” said Hank Greely, a Stanford University bioethicis­t. “The advantage with gene editing is you can put the gene in where you want it.” Finally, some fear that the virus could get into other places like the heart, or eggs and sperm where it could affect future generation­s. Doctors say built-in genetic safeguards prevent the therapy from working anywhere but the liver, like a seed that only germinates in certain conditions.

This experiment is not connected to other, more controvers­ial work being debated to try to edit genes in human embryos to prevent diseases before birth—changes that would be passed down from generation to generation.

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