Existing techniques only compensate for mutations
A new type of gene therapy allows scientists to fix DNA defects directly. That’s a potentially revolutionary improvement on present gene therapy techniques, which introduce working genes to cells — but not into the genetic library itself.
“This is a major leap of the technology,” says John Rossi, a molecular geneticist at the Beckman Research Institute of City of Hope in Duarte, Calif.
Working with newborn mice, researchers led by Katherine High at the Children’s Hospital of Philadelphia found that molecular editors called zinc finger nucleases can correct a genetic mutation that leads to the blood-clotting disorder hemophilia. Fixing a mistake in the gene for blood coagulation factor IX allowed the animals to make about 3 percent to 7 percent of normal levels of the protein, High and her colleagues report online June 26 in Nature. Even such modest increases are therapeutically meaningful, High says. People who make about 5 pe