Costing some $15 million, researchers put the final piece of a scientific puzzle on the horse genome sequence that totalled
2.7 billion DNA base pairs.
The early February announcement from the Massachusetts Institute of Technology's (MIT) Broad Institute that Equus caballus was added to the growing list of species genetically sequenced followed last year's unveiling of the dog. The map went global
and made available to genetics researchers to spur new studies.
The advancement for veterinary medicine ends more than a decade of research and opens possibilities as vast as the molecule
of life itself. In other words, the map has been built, and it paves the way for faster, cheaper exploration.
Twilight's contribution: A blood sample was enough to give geneticists at MIT's Broad Institute the tools to sequence the
equine genome. Twilight is a research Thoroughbred at Cornell University's College of Veterinary Medicine.
It's about recognizing changes at the genetic level that influences health and disease, says Doug Antczak, VMD, PhD, the Dorothy
Havemeyer McConville Professor of Equine Medicine at Cornell's Baker Institute. Antczak's team participated in collaborative
research and owned the DNA-donor Thoroughbred Twilight.
"I never expected to have this completed in my working lifetime. All the things that can be done at the genome level, you
can do in horses. That was not true a year ago," Antczak tells DVM Newsmagazine.
There are 80 known conditions in horses that are genetically similar to disorders seen in humans. The list starts with musculoskeletal
problems and ends with cardiovascular and respiratory diseases. The next leg of this trip will be aimed at diagnostic testing
methods or continuing research into new treatments.
- A DNA sequence from any gene in the library will be available to researchers so they can focus on that gene within the context
of the horse. A process that used to take three months to identify will now only take technicians about 30 minutes.
- The development of an SNP chip, a collection of DNA spots on a slide for genome-wide molecular experiments, could lead to
research investigating polymorphisms and variation in the genome or be directed toward gene expression. For example, researchers
could be comparing lymphocytes from horses infected with herpes virus or free of herpes virus, or identify which genes are
expressed when making an immune response to herpes (also called a gene expression array).
The findings are big, but the potential this work holds on improving the health of the horse is even bigger.
The sequencing is a culmination of work conducted by 20 institutions internationally and coordinated through Dr. Ernie Bailey
of the University of Kentucky's Gluck Equine Research Center. Funded by the National Human Genome Research Institute, one
of the National Institutes of Health, the genetics team at Broad carried out the sequencing and assembly of the horse genome.
"Just imagine yourself flying. We started this project at 30,000 feet. You can imagine that you don't see a great level of
detail. Now with the sequence, we will be working at the ground level. That's a major accomplishment," Antczak says.
The landing took Broad's Kerstin Lindblad-Toh's team one year, a far faster and cheaper ride compared to the eye-watering
13-year, $2.7-billion price tag for the human genome still lauded as one of the greatest feats in science exploration. The
process improved, Antczak reports, and the velocity of mapping work accelerated exponentially.
"The horse community really hit the jackpot last year when NIH added the species to the list they are sequencing," Antczak
explains. "The horse became an attractive species to NIH both for its value to human medicine and its application to human
medicine. But they did so on the basis of work that has gone on by horse geneticists in an organized fashion."