A recent US government-funded study of the genetic map of an inbred boxer named Tasha has not only helped explain how Great Danes differ from jackals, but but could offer insights into cancers, blindness and epilepsy, the researchers said.
The science journal Nature, published the findings of researchers at 15 institutions: and how they compared the genetic blueprint of the boxer with 10 other breeds. They also compared the dog genome to the already-completed maps of human genes, mice, rats and chimpanzees.
The team sequenced the 2.4 billion letters of Tasha's DNA, representing 39 pairs of chromosomes. There lies one big difference between dogs and people -- human genes are found on just 23 pairs of chromosomes.
They also catalogued 2.5 million single-nucleotide polymorphisms (one-letter changes in the genetic code) that differ among the 10 breeds of dogs studied.
The genes that make some dogs big and others little, that give some dogs long snouts and others pushed-in faces, and that predispose some dogs to certain diseases provide a convenient laboratory for studying biology, medicine and evolution.
"The hundreds of years of careful inbreeding to produce the various breeds have delivered a geneticist's dream model for human genetic disease," Hans Ellegren of Uppsala University in Sweden wrote in a commentary. "" Lander said.
Elaine Ostrander, chief of cancer genetics at the National Human Genome Research Institute, said dog genetics could help narrow down the search for human disease genes. "The leading causes of death in dogs are a variety of cancers, and many of them are very similar biologically to human cancers, Cancers that dogs get are exactly the same as the cancers that we get" Ostrander said.
"It's going to make the identification of many disease genes 50 times easier," Dr Eric Lander, a gene expert at the Broad Institute at the Massachusetts Institute of Technology and Harvard University who helped coordinate the study, told a news conference. It ought to be possible in the next three to four years to identify a gene for bone cancer in dogs. Until now we only had little shreds of the dog genome. We now have the entire book from end to end, ready to read.”