In the end, 27 puppies were born, but
only two, a female and a male, had disruptions in both copies of the myostatin gene.
The researchers named the female beagle
Tiangou, after the “heaven dog” in Chinese
myth. They named the male Hercules.
Lai and his colleagues reported that
in Hercules, the gene editing was incomplete, and a percentage of the dog’s muscle
cells were still producing myostatin. But
in Tiangou, the disruption of myostatin
was complete, and the beagle “displayed
obvious muscular phenotype,” or characteristics. For example, her thigh muscles
were larger than those of her littermates.
The ease with which gene editing can
be carried out has raised worries that
humans could be next. Yet at least some
researchers think gene-edited dogs could
put a furry, friendly face on the technology. George Church, a professor at Harvard University who leads a large effort
to employ CRISPR editing, said in an
interview that he thinks it will be possible to improve dogs by using DNA edits
to let them live longer or simply make
Church said he also believed the
alteration of dogs and other large animals could open a path to eventual gene
editing of people. “Germ-line editing of
pigs or dogs offers a line into it,” he said.
“People might say, ‘Hey, it works.’”
Man’s best friend is now his newest genetic-
Scientists in China say they are the first
to use gene editing to produce customized
dogs. They created a beagle with double
the usual amount of muscle mass by deleting a gene called myostatin. The dogs have
more muscles and are expected to have
stronger running ability, which is good for
hunting, police, and military applications,
Liangxue Lai, a researcher with the Key
Laboratory of Regenerative Biology at the
Guangzhou Institutes of Biomedicine and
Health, said in an e-mail.
Lai and 28 colleagues reported their
results in the Journal of Molecular Cell
Biology, saying they intend to create
dogs with other DNA mutations, includ-
ing ones that mimic human diseases such
as Parkinson’s and muscular dystrophy.
“The goal of the research is to explore an
approach to the generation of new disease
models for biomedical research,” says Lai.
“Dogs are very close to humans in terms of
metabolic, physiological, and anatomical
Lai said his group had no plans to
breed the extra-muscular beagles as pets.
Other teams, however, could move quickly
to commercialize gene-altered dogs,
potentially editing their DNA to change
their size, enhance their intelligence, or
correct genetic illnesses. A Chinese insti-
tute, BGI, said in September it had begun
selling miniature pigs, created via gene
editing, for $1,600 each as novelty pets.
Gene editing employs newly developed techniques that let scientists easily disable genes or rearrange their DNA
letters. The method used to change the
beagles, known as CRISPR-Cas9, is particularly inexpensive and precise. Lai’s
work is part of a large Chinese effort to
modify animals using CRISPR. The list
of animals already engineered using gene
editing in China includes monkeys (see
10 Breakthrough Technologies, “Genome
Editing,” May/June 2014.)
Lai and his team introduced the
gene-editing chemicals—a DNA-snip-ping enzyme, Cas9, and a guide molecule
that zeroes in on a particular stretch of
DNA—into 65 dog embryos. Their objective was to damage, or knock out, both
copies of the myostatin gene so that the
beagles’ bodies would not produce any
of the muscle-inhibiting protein that the
Genome engineering has created an extra-muscular beagle.
Are we on our way to customizing the DNA of our pets?