Dog Genome Expected to Enhance Cancer Research

In December, the BBC published an interesting article on the role that the decoded dog genome may play in helping to understand and treat cancers in human beings.

Initial work on sequencing the dog genome was finished in the summer of 2004. Human beings and dogs share many of the same cancers, including bone cancer, skin cancer and lymphoma.

Ironically, thousands of years of human-influenced breeding of dogs means it will be relatively easy to discover which genes contribute to cancer in dogs. Because of the way dogs have been breed, there is little genetic variation within purebred dogs and many breeds of dogs began with a very small number of dogs, so they had little genetic variation to begin with.

As geneticist Matthew Breen told the BBC, this means that cancers in dogs are likely “being switched on by very few genes — maybe even just one — which exert a very large effect.”

This provides an excellent example of why animal models are often superior to using human models of a disease. As the BBC notes,

In order to figure out where a cancer-causing gene is located in an animal’s genome, scientists use genetic “markers,” which are sequences that differ slightly between different dogs and have a known location on a chromosome.

When disease-affected animals consistently have a certain marker, and healthy animals do not have it, then there is a good chance that a disease gene is located very close to that marker.

These analyses are difficult to do in humans, because geneticists need to look at DNA samples from many people in an affected family in order to pin down the gene’s location.

Most human families are too small – and have too few generations alive at the same time – for a sufficient number of samples. Dog families, on the other hand, have short generations and many offspring.

Such a technique was used to locate a gene in German shepherds that is responsible for kidney cancer, which also turned out to be a recently identified suspect in kidney cancers in human beings.


Dog genome boosts cancer research. BBC, December 29, 2004.

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