Researchers from Broad Institute of MIT and Harvard have published the entire genome sequence of dog (man's best friend). Human beings share similarity of their ancestral DNA with dogs and the complete sequencing of the dog genome would provides a powerful tool for identifying genetic factors that contribute to human health and disease as both humans and dogs are mostly affected by cancers and the sequencing will help in identifying treatments for hereditary cancers.
The Researchers isolated the DNA sequence covering nearly 99 percent of the dog genome, from a female boxer named Tasha. The boxer was chosen as a representative of the average purebred dog to produce what has become a reference sequence for the dog genome community. Using the sequence information as a genetic "compass," they navigated the genomes of 10 different dog breeds and other related canine species, including the gray wolf and coyote. In this sampling, they pinpointed tiny spots of genetic variation, called single nucleotide polymorphisms (SNPs), which serve as recognizable signposts that can be used to locate the causes of genetic disease. Dr. Ostrander's laboratory maps genes responsible for cancer susceptibility in canines and humans, including breast and prostate cancers. In addition, Dr. Ostrander was the lead author of the white paper that provided the biomedical rationale for sequencing the dog genome.
The researchers found that the certain sequence in the gene of dogs were present as small elements that are crowded around just a small fraction of the genes in the genome. Future studies of these clusters may give scientists the critical insight needed to unravel how genomes work. Other interesting observations emerged from this cross-genome analysis. The international team of researchers also identified roughly 2.5 million single nucleotide polymorphisms (SNPs) sprinkled throughout the dog genome. SNPs are variations in the DNA code, some of which contribute to diseases or the overall health of a dog. SNPs also can be used to create a set of coordinates with which to survey genetic changes, both within and across dog breeds. These efforts revealed that individual breeds have maintained a large amount of genetic variability, despite their long history of restrictive breeding. In practical terms, this means that future efforts to locate disease genes in dogs can be much narrower in scope than comparable human studies, requiring a smaller number of genetic markers and DNA samples collected from the blood or cheek from only a few hundred dogs.
Scientists in the canine genetics community worldwide are currently tackling this problem by applying the knowledge gained from SNP analysis to find disease genes. To this end, the dog-owner community is an essential collaborator. "We deeply appreciate the generous cooperation of individual dog owners and breeders, breed clubs and veterinary schools in providing blood samples for genetic analysis and disease gene mapping," said Dr. Lindblad-Toh, who is the paper's first author. "Without their interest and help we could not be doing this work."