Cleaning up your genetic code

dna

(CNN) – Patients dealing with devastating genetic conditions like cystic fibrosis or sickle cell anemia today can do little except manage their symptoms. But in the future, doctors may be able to address the root cause of these diseases by infusing a copy of “correct” genetic material to patch up the problem, cell by cell.

Experimental gene therapy has advanced in recent years to treat blindness and Parkinson’s disease in people. Current therapies strap “good” DNA to the back of a virus, which carries it to cells throughout the body.

Compared to early attempts, which had dangerous side effects, the results have been promising, says Mark Levin, a partner with Third Rock Ventures, which is bankrolling several new gene therapy companies.

One of those companies, Voyager Therapeutics, is targeting Parkinson’s and other neurological disorders. Another, Bluebird Bio, is running a clinical trial for patients with childhood cerebral adrenoleukodystrophy, the disease that inspired the movie “Lorenzo’s Oil.”

But delivery by virus is still a blunt approach. The holy grail, says Bluebird boss Nick Leschly, is the ability to replace faulty DNA. That’s the long-term goal of Editas Medicine, whose technology literally edits out harmful mutations – at least in a test tube.

“Some people describe what we do as molecular surgery,” says Kevin Bitterman, Editas’ interim CEO. Eventually, he hopes to develop DNA repair therapies for everything from Alzheimer’s to heart disease.

As genetic technology becomes more accessible, doctors could become more like computer programmers than pharmacists, says Austen Heinz, who runs Cambrian Genomics. The company uses 3-D printing to make synthetic DNA for drug companies. With a few keystrokes, Heinz says, a future doctor/programmer could rewrite our genetic program and print off a few million copies on a laser printer.

The biggest hurdle, say Heinz and others, is knowing which genes to target. “The next step is to edit the embryo to fix simple disorders, like cystic fibrosis or Huntington’s, that are caused by a single gene,” he says. “But most diseases are really complex. In the near term, it’s beyond human comprehension.”

Yet he says the challenges can be overcome. “The good news is that you don’t have to totally understand autism or mental disorders to fix them. You just have to clean up the (genetic) code.”

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