"Scientists should refrain from studies that alter the genome of human
embryos, sperm, or egg cells, researchers warn in a commentary published today
in Nature.

In it, they sound the alarm about new genome-editing
techniques known as CRISPR and zinc-finger nucleases that make it much easier
for scientists to delete, add, or change specific genes. These tools have made
it possible to make better animal models of disease and more easily study
the role of individual genes. They also hold the promise of
correcting gene mutations in patients, whether in blood cells, muscle cells, or
tumor cells.

But scientists have also used the technology to make
genetically altered monkeys. And there
are rumors that some researchers are trying the same technique on human
embryos, MIT Technology Review reports.

That is
unsafe and unethical, say Edward Lanphier and four other researchers in their commentary. Ethically
justifiable applications “are moot until it becomes possible to demonstrate safe
outcomes and obtain reproducible data over multiple generations,” they write.
They call for a moratorium on any experiments that would edit genes in sperm
cells, egg cells, or embryos while scientists publicly debate the scientific and
ethical consequences of such experiments. The recent discussion of mitochondrial DNA replacement therapy in
the United Kingdom could be a model, they suggest.

They hope that such
a discussion would help the public understand the difference between genome
editing in a person’s somatic cells—cells other than sperm and egg cells—and
editing in cells that could pass the changes on to future generations, says
Lanphier, who is president and CEO of Sangamo BioSciences in Richmond,
California, a company that hopes to use gene-editing technology to treat
patients. “There’s an important and clear ethical boundary between genome
editing in somatic cells versus in the germ line.”

George Daley, a
stem cell researcher at Boston Children’s Hospital and Harvard Medical School,
agrees that a public debate is important. Among scientists, he says, there is
broad consensus that at the moment “it’s far too premature and we know far too
little about the safety to make any attempts” at modifying germ cells or
embryos. But that will eventually change, he says. “There needs to be broad
public debate and discussion about what, if any, are the permissible uses of the
technology.”