NHGRI
Instructive pup.
Thanks to Tasha, researchers have a much better handle on the dog
genome.
Dog Genome Has Its Day
By Michael Balter 7 December 2005
Man is about to learn a lot more about his best friend. Scientists report this week the
first high-resolution genome sequence of the domestic dog, Canis familiaris. The
findings may provide clues to what makes dog breeds look so different and shed
light on what separates us from our trusted companions.
Judging from the close relationship many people have with their dogs, it might be
hard to believe that the evolutionary lineages leading to humans and canines split
some 95 million years ago. Despite this distance, some 360 genetic disorders found
in humans have also been identified in dogs, and both species suffer from ailments
such as cancer, heart disease, and hip dysplasia. Researchers have been keenly
interested in the dog genome for what it might tell them about the genetics of
disease, as well as the basis for the amazing variety of shapes and sizes represented
by the roughly 400 breeds of domestic dog.
Now they have an exciting new tool: the genome of a pure bred female boxer named
Tasha. Detailed 8 December in Nature, Tasha's sequence has five times higher
resolution than a rough draft of a poodle genome reported two years ago by
sequencing pioneer J. Craig Venter and colleagues (Science, 26 September 2003, p.
1898). The higher resolution allowed the team, led by genome researchers Eric
Lander and Kerstin Lindblad-Toh of the Broad Institute of Harvard University and the
Massachusetts Institute of Technology, to come to a number of important
conclusions. For example, the dog has about 19,000 genes, somewhat less than the
22,000 estimated for humans. At least 70% of these genes have human counterparts,
and about 5% are identical to ours.
The team also found that certain genes that appear to have undergone accelerated
evolution in the human line, including some related to brain function, have also
undergone accelerated evolution in the dog. The results "cast serious doubt" on
recent high-profile claims that rapid changes in such genes played a role in the
evolution of unique features of the human brain (ScienceNOW, 20 April), says
evolutionary geneticist John Fondon III of the University of Texas Southwestern
Medical Center in Dallas.
The new sequence should be a boon to the study of disease and the genetics behind
breed differences, says genome researcher Ewen Kirkness of The Institute for
Genome Research in Rockville, Maryland, who worked on both the poodle and boxer
sequencing projects. Indeed, the December issue of Genome Research features six
papers that use the new sequence information, combined with partial sequencing of
other breeds, to investigate a wide range of subjects from canine cancer to the
genetics of variation in the size and shape of the dog skeleton. "We can now expect
to see a gold rush" of new discoveries, says Fondon.