Doctors’ bid to fix genes inside patient in world first
Health & Wellness / 16 November 2017, 11:00am / COLIN FERNANDEZ SCIENCE CORRESPONDENT
SCIENTISTS have for the first time tried to permanently alter DNA inside a patient’s body to cure a disease.
Brian Madeux, 44, the first to undergo the gene therapy, suffers from a rare genetic disease previously thought incurable called Hunter Syndrome, in which his liver does not make a key enzyme.
Scientists have edited genes before, but only outside the body in a lab. They have not been able to direct where the altered genes go when reinserted into the body, meaning treatments sometimes do not work, or offer only temporary results.
But the new technique is much more precise. A patient is injected with a virus that acts as a vessel carrying two key components – a new gene to correct a faulty one, and proteins called ‘zinc finger nucleases’, which are like scissors programmed to locate a specific section of DNA.
The virus travels into cells in the liver, where the zinc fingers cut the right portion of DNA and insert the correct gene.
It is thought this will trigger Madeux’s liver to start producing the enzyme he needs. Madeux, a chef, had the treatment at the Oakland hospital in California. According to his doctor, Dr Paul Harmatz, just 1 percent of liver cells need to be corrected to treat the disease. Madeux said: ‘It’s kind of humbling to be the first to test the technique. I’m willing to take that risk. Hopefully it will help me and other people.’
It will take three months before it is clear whether the technique is working.
Dr Sandy Macrae, of Sangamo Therapeutics, which is testing the treatment, said it is like ‘invisible mending’ and that the new gene ‘becomes part of your DNA and is there for the rest of your life’.
Hunter Syndrome patients suffer a range of issues including heart and joint problems, breathing trouble, hearing loss and brain damage, with many in wheelchairs.
Weekly doses of the missing enzyme can ease symptoms, but are hugely expensive and do not prevent brain damage.
Madeux, who lives near Phoenix, has had 26 operations and last year nearly died from pneumonia. Gene editing cannot fix damage already suffered, but it would stop the need for the weekly treatments.
Initially up to 30 adults will get the therapy to test its safety, but the goal is to treat children before damage occurs.