Equine Genomics: A New
Frontier with Great Potential
Genomics is the study of the
complex molecular chains that constitute an organism’s unique genetic
heritage. Mapping the genome (DNA) of the horse can broaden our
understanding of what makes horses tick and produce wide-ranging applications
in their breeding, care and health research.
In the last ten years interest
in genome research has focused on genomes of livestock and poultry to
understand how various genes function and interact. The 1990 Farm Bill
officially recognized the potential of agricultural genomics when it authorized
a U.S. Department of Agriculture Genetics Resources Program. In 1993 the
National Research Support Project was organized to coordinate the genome mapping
efforts. That effort now includes horses and includes Species Genome
Committees. The Horse Genome Coordinator is Dr. Ernest Bailey of the
The USDA is responsible for
supporting research on agriculturally-important animals, and the horse is
clearly included in this group. While significant support has been provided
for horse genomics research, it lags significantly behind work supported for
cattle, chickens, pigs, sheep and aquaculture. Already, there is a
complete genome sequence for cattle and chickens. Genome sequencing is
underway for pigs and sheep. The USDA has been a strong advocate for this
work.
One problem is the small size
of the research community working on the horse. Another problem is a bias
within the agricultural community towards work on “food and fiber”
animals. The horse, providing neither, fares poorly when “food and fiber”
is a criteria. “However, the largest problem is the perception within the
USDA that the horse industry does not support the use of genomics in research,”
suggests American Horse Council President
The National Human Genome
Research Institute recently announced that they would conduct a low level sequencing
effort on the horse genome. This work will provide DNA sequences for 80%
of the horse genome. “Such information will enable equine scientists to
do significant work in the areas of gene expression, genetics, and functional
genomics and permit research in physiology, immunology, nutrition,
pharmacology, and metabolic diseases,” according to Dr. Bailey.
Currently, the horse gene map
includes 2,000 genes or genetic markers that can be used in family studies to
find genes responsible for diseases. This is the approach used to
identify the genes responsible for hyperkalemic periodic paralysis (HYPP),
severe combined immunodeficiency disease (SCID), and overo lethal white foal
syndrome (OLWFS). But horse families cannot be readily assembled to study
every hereditary trait of interest for the horse. Fortunately there is another
approach, called an association study, that can circumvent this problem.
To pursue fully this research a complete horse genome sequence is needed.
Federal funding is needed to
supplement private funding to support continued research. But support
from the horse industry is needed and a clear message must be sent to Congress
and the Department of Agriculture about the importance of genome
sequencing. Congress will begin putting together the next farm bill soon,
even though it will not be considered until 2007. Funding for genomics
research will likely be included in that package. “The horse industry
must let Congress know that there is support for mapping the genes of horses,”
said Hickey. “Congress must be told the benefits that can be realized
from this research to an industry that involves 9.2 million horses, has an
economic impact of $102 billon on the
“The point is not to change the
way that we breed and train horses. Rather it is to make us more
effective at what we already do. With a complete mapping of the horse
genome sequence we will see new drugs, vaccines, diagnostic tests, and
management programs developed to benefit the health and welfare of horses,”
noted Dr. Bailey.
Research into mapping the
genomes of horses must continue. For that to happen there must be support
from the horse industry.