Scientists at Harvard and MIT’s Broad Institute have mapped the genes
of man’s best friend, the dog, in the hopes of uncovering
insights into diseases that affect both humans and canines.
The results, published in the December 8 issue of the science journal
Nature, include the first comparative analysis of three mammalian
genomes—human, mouse, and dog.
Tarjei S. Mikkelsen, a graduate student at the Harvard-MIT Division of
Health Sciences and Technology (HST) and one of the leaders of the
research project, said that researchers were surprised that the
sequences that humans had in common with dogs were the same sequences
that humans shared with mice.
The similarities between the three mammalian species allow researchers
to identify the most biologically important genetic elements in humans,
“This is a significant step toward assembling a complete parts list for the human genome,” he added.
Mikkelsen and fellow researchers have found that the majority of the
DNA common to all three mammals was significant for their growth and
Kerstin Lindblad-Toh, the first author of the Nature paper and
co-director of the Genome Sequencing and Analysis program at the Broad,
said that because the DNA sequences, or haplotypes, are much longer in
dogs than in humans, a canine genetic map can be used instead of the
human genome to identify the haplotypes responsible for certain human
According to Karlsson, researchers must examine at least 300,000 single
nucleotide polymorphisms (SNPs) in thousands of patients to find the
genes that cause disease in humans. “Because of their unique genomic
organization, we need about 30 times fewer SNPs and only a few hundred
volunteers to accomplish this task in dogs,” Karlsson said in a
statement from the institute.
According to the new research, dogs have about 19,300 genes. Human beings have about 22,000 genes.
Broad Institute researchers are currently working to map an increasing number of mammal genomes, according to Lindblad-Toh.
“We are sequencing eight, soon will be sixteen, different mammals at lower coverage, including the opossum,” she said.
The Broad Institute, a joint venture of Harvard and MIT founded in
2003, received an additional $100 million in funding from
philanthropists Eli and Edythe L. Broad earlier this month.