Human, Dog Genomes Similar, Study Finds

Stefan Lovgren
for National Geographic News
September 25, 2003

Scientists have completed a rough sketch of the canine genome. The results may explain why dogs are humans' best friend: Their genes are similar.

The successful sequencing of the dog genome sheds light on the structure and function of the human genome, and could help researchers better understand diseases that affect both humans and dogs.

"Dogs suffer from more than 350 genetic disorders, many of which resemble human conditions," said Ewen Kirkness, a molecular biologist at the Institute for Genomic Research in Rockville, Maryland, who led the research. "The genes responsible for these are probably constant to humans and dogs."

Kirkness and his team covered the genome of a standard poodle one and a half times. That means the amount of DNA sequence they generated is one and a half times the length of the genome. In contrast, a high-level method recently used to sequence the human and mice genomes covered those genomes eight times.

While the shallow sequencing method does not give as complete a picture of the genome as the high-level sequencing method, it is far less expensive. Kirkness believes his technique will allow scientists to sequence genomes of species they could otherwise not afford to study.

"We can learn a lot more about mammalian evolution on a molecular level by applying this technique to a wider diversity of species," said Kirkness. "Species like whales and elephants can tell us a lot. But from a purely financial standpoint, they will [not] be candidates for complete sequencing [anytime soon]."

The research, which was started in 2001, is described in tomorrow's issue of the journal Science.

Dogs and Humans

The rough sequencing of the dog genome is the latest advance in the field of comparative genomics. To date, researchers have sequenced the human, mouse, rat, worm, fly, and fungi genomes.

The sequencing indicates that dog and human genomes are more similar to each other than either is to the mouse, though it appears the dog lineage diverged first from the common ancestor.

Dogs are important to researchers because they can be used as biomedical models for understanding human diseases. The top ten diseases among purebred dogs include several that afflict humans, including cancer, epilepsy, heart disease, allergy, retinal disease and cataracts.

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