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The dog show: few genes lead to many breeds

Vincent Shen

Using SNP genotyping, researchers have found that relatively few genomic regions are responsible for the vast variation found in dog breeds.

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Six years since the sequencing of the dog genome, National Institutes of Health (NIH) researchers have discovered that relatively few genomic regions dictate a dog’s physical appearance in the largest and highest-resolution single-nucleotide polymorphism (SNP) mapping study to date.

The collaboration, led by Elaine Ostrander, chief investigator at the National Human Genome Research Institute (NHGRI), estimated that each type of dog trait—body size, skull shape, ear position, height, limb/tail, coat color, snout dimensions—is governed by one to six genes. Researchers found that only 51 regions on the genome actually affect those traits.

Elaine Ostrander is working to decipher which SNPs correspond with which dog traits. Source: Science

“People interested in similar systems will look at those genes even if they don’t use the dog system,” said Ostrander. “They’ll look at the comparative regions and see what genes are interesting.” Because humans and dogs share many disorders including diabetes, cancer, epilepsy, and obesity, researchers hope these results will help inform human disease research.

Using SNP chips to discover new regions responsible for variation, the researchers analyzed 60,948 SNPs in the genomes of 900 dogs of 85 different breeds. Furthermore, about 100 wild canids were used, which is not common in genomic studies. The majority of samples were obtained from animals at dog shows, obedience trials, performance events, and specialty events sponsored by the American Kennel Club (AKC). Other samples came from veterinaries or licensed assistants who drew serum from dogs whose owners had signed a written consent.

“We published numerous papers on body size, and we revisited it in this paper to see if a larger data set would give us additional information,” said Ostrander, “which it did. It highlighted some of the same genes and identified some of the new ones.”

Currently, Ostrander is working to understand how combinations of relatively few genes determine body size and shape. “There’s a continuum of body size from 2-pound dogs to 200-pound dogs, and it’s a small number of genes that probably control most of that variation,” said Ostrander.

The paper, “A simple genetic architecture underlies morphological variation in dogs,” was published 10 Aug. 2010 in PLoS One.

Keywords:  dog genome snp