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Horse Genome Project

RECENT NEWS

International Equine Genome Mapping Workshop
The 8th Dorothy Russell Havemeyer Foundation International Equine Genome Mapping Workshop took place near Newmarket, UK from July 22 to 25, 2009...[more]

MEDIA ECLIPSE AWARD
Writers at the Louisville Courier Journal recently won the 2008 Media Eclipse Award for journalism based on an article about Thoroughbred racing and break-downs. They published a 3 part story, including genetics, track surfaces and medications. In connection with the genetics section they interviewed several members of the Horse Genome Project. See the accompanying links for the full stories on the 2008 Media Eclipse Award and the article itself.

Courier-Journal Web site wins award for horse project
Genetics may hold key to Injury-prone horses
[December 2008]

HORSE GENOME SEQUENCE COMPLETE
The first draft of the horse genome sequence was recently completed and deposited...
[JAVMA News, April 2007]

HORSE GENOME ASSEMBLED
Data on Equine Genome Freely Available to Researchers Worldwide
[NIH News, February 2007]

HORSE GENOME SEQUENCED
The first genome map of a horse is complete, providing scientists with new tools for investigating equine disease. [ April 2006]

 

APPLICATIONS OF GENOME STUDY - SIMPLE HEREDITARY DISEASES

Horses have been bred for performance. Only strong, healthy animals were chosen to continue the next generation. Therefore, there are not many purely genetic diseases among horses.  However, the few that do occur pose serious problems to horse owners and breeders. Work by scientists using genome information has led to the development of simple diagnostic tests to detect these genes.

HYPP:  Hyperkalemic periodic paralysis (HYPP) is a muscle disease found among Quarter horses.  Affected horses have very muscular appearances but are subject to muscular collapse under stress.  Scientists from California and Pittsburg, PA identified a gene defect based on the occurrence of a similar defect in people.  The gene encodes a potassium channel for cells. Cells with the mutation are unable to regulate the amount of potassium and the muscles undergo involuntary contractions. The repeated contractions also constitute exercise and the muscles become large and prominent. This appearance is desirable for Quarter horse shows and breeders have selected for the trait.  However, its effect on performance makes it undesirable for riding.  HYPP is caused by a dominant gene and a single copy of the gene can cause the disease. Horses with two copies of the disease appear to be more severely affected.  A molecular test was developed by the scientists at the University of California and Pittsburgh and is commercially available.
 
SCID:  A rare genetic defect in Arabian horses results in a complete lack of an immune system. Affected horses die within 3 months of birth due to opportunistic bacterial, viral or fungal infections.  The condition is called severe combined immunodeficiency disease (SCID).  SCID is caused by a recessive gene. This means that affected foals inherit a copy of the gene from both parents. Horses with one copy of the gene are unaffected and called carriers.  The gene defect was identified by scientists at the University of Texas and a molecular genetic test developed.  Approximately, 8% of Arabian horses in America are carriers.  However, as long as carriers are not mated to other carriers, no affected foal need ever be produced.
  
JEB:  A skin disease was found among Belgian draft horses that resulted in sloughing of skin in newborn horses.  Since the skin is an important barrier to bacterial infection, this defect results in serious bacterial diseases and death of affected foals.  The genetic basis was recessive in that carriers of the gene appeared normal but their offspring might have the disease.  The skin disease of horses appeared very similar to a disease in people called junctional epidermolysis bullosa (JEB). The gene in horses that corresponds to the gene responsible for a similar human disease was investigated by French scientists. They identified the gene mutation and developed a molecular DNA test to identify carriers of the disease gene.

HERDA:  Hereditary equine regional dermal asthenia (HERDA) is a rare degenerative skin disease of Quarter horses.  It is caused by a recessive gene and two copies are necessary to manifest the disease.  Foals appear normal at birth but by the age of 1.5 years they begin to develop skin lesions in response to mild abrasion.  Scientists at the University of California mapped and identified the genetic mutation responsible for the disease.  A molecular genetic test is available to detect carriers of the disease-causing gene.

OLWFS:  Overo lethal white foal syndrome (OLWFS) is directly related to the Overo gene (O). One copy of the gene produces an attractive white hair color pattern.  Two copies of the gene cause developmental defects in the foals causing it to appear entirely white and to die shortly after birth.  As noted above, scientists at the University of Minnesota, University of California and from Australia discovered the cause of the condition based on its similarity to Hirschsprung’s disease.  A molecular genetic test is available.

GBED: Glycogen branching enzyme deficiency (GBED) is a simple recessive lethal condition of Quarter horses and Paint horses that disrupts glycogen metabolism. The genetic basis of the disease was determined and a molecular DNA test developed by scientists at the University of Minnesota.

 

 

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