Combining the DNA of 3 People Raises Ethical Questions

"In a darkened lab in the north of England, a research associate is intensely focused on the microscope in front of her. She carefully maneuvers a long glass tube that she uses to manipulate early human embryos."

"'It's like microsurgery,' says Laura Irving of Newcastle University."

"Irving is part of a team of scientists trying to replace defective DNA with healthy DNA. They hope this procedure could one day help women who are carrying genetic disorders have healthy children."

"'We are talking about conditions for which there is currently no cure,' says Dr. Doug Turnbull, a professor of neurology at Newcastle University who is leading the research. These mitochondrial diseases are caused by hereditary defects in human cells."