Turnaround: 3-5 business daysTurnaround: 7-10 business days
Price: $45.00Price: £35.00
Breeds: American Saddlebred, Kentucky Mountain Saddle Horse, Mixed Breed, Saddlebred, Saddlebred/Thoroughbred, Saddlebred/Warmblood, Spotted Saddle Horse, Unspecified
Description
Junctional Epidermolysis Bullosa (JEB) is an inherited skin disease also known as Red Foot Disease or Hairless Foal Syndrome. Variations of the disorder affect Belgian Draft horses, American Saddlebred horses, and relatives of these breeds. This test detects the JEB2 variant found in American Saddlebred horses and related breeds. In Saddlebreds the condition was previously known as epitheliogenesis imperfecta (EI), before the causative gene was identified.
JEB2 is caused by a large deletion in the LAMA3 gene (g.3724_10312del6589) spanning several exons. LAMA3 encodes one of the three subunits of laminin-5, a protein essential to anchoring skin and mucosa to the underlying tissue, and the deletion results in a non-functional protein.
Affected foals are typically born alive with few signs. Four to five days after birth, skin lesions begin to develop at pressure points around the body and quickly spread into larger patches. Because laminin-5 is also involved in hoof attachment, the foal begins to lose the hoof, which may detach entirely. Foals may also develop oral ulcers and eroded enamel, and are typically born with incisor teeth, whereas normal foals do not develop teeth until around eight days of age.
There is no cure for JEB. As the condition worsens, foals develop severe infections and suffer increasing pain and discomfort. Affected foals die from these infections or are euthanized within 3 to 8 days after birth.
JEB is inherited as an autosomal recessive trait, so a foal must inherit two copies of the variant to be affected. Carriers have one copy and show no signs of disease. If two carriers are bred, each foal has a 25% chance of being affected and a 50% chance of being a carrier. Because affected foals do not survive to breeding age, every affected foal comes from a carrier-to-carrier mating. Carriers need not be removed from the breeding pool; a carrier bred to a clear horse will never produce an affected foal, so DNA testing allows breeders to keep valuable bloodlines while avoiding affected foals.
Animal Genetics offers DNA testing for both the JEB1 variant found in Belgian Draft horses and the JEB2 variant found in American Saddlebred horses.
Possible results
| Genotype | Description |
|---|---|
| J2/J2 | Affected: Horse has two copies of the JEB2 variant and is expected to develop signs of the disorder. |
| N/J2 | Carrier: Horse has one copy of the JEB2 variant and is not expected to show signs of the disorder. Each offspring has a 50% chance of inheriting the variant. |
| N/N | Clear: Horse does not carry the JEB2 variant and cannot pass it on to offspring. |
Breeds Affected
American Saddlebred, Kentucky Mountain Saddle Horse, Saddlebred, Saddlebred/Thoroughbred, Saddlebred/Warmblood, Spotted Saddle Horse
Reference
[PMID: 19016681]