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Discussion on 'Research Summary: ASB JEB pathogenesis and test
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Moderator:
DrO
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Posted on Friday, Nov 21, 2008 - 8:47 am:
To clarify the above abbreviations let me write it out: It is now confirmed that American Saddlebreds do have the defective gene for junctional epidermolysis bullosa in their gene pool. A random survey of 175 foals found the gene in 9 foals so the incidence in this population to be about 6%. However since this is a recessive gene, these individuals with just one gene will appear normal. Only when they match up at breeding so the foal is homozygous does the foal have actual disease. Most important is that a test is available for this gene so with a diligent horse owing population it can be reduced and possibly removed from the population.
DrO
Anim Genet. 2008 Nov 11;
Partial deletion of the LAMA3 gene is responsible for hereditary junctional epidermolysis bullosa in the American Saddlebred Horse.
Graves KT, Henney PJ, Ennis RB.
Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA.
Summary Laminin 5 is a heterotrimeric basement membrane protein integral to the structure and function of the dermal-epidermal junction. It consists of three glycoprotein subunits: the alpha3, beta3 and gamma2 chains, which are encoded by the LAMA3, LAMB3 and LAMC2 genes respectively. A mutation in any of these genes results in the condition known as hereditary junctional epidermolysis bullosa (JEB). A 6589-bp deletion spanning exons 24-27 was found in the LAMA3 gene in American Saddlebred foals born with the skin-blistering condition epitheliogenesis imperfecta. The deletion confirms that this autosomal recessive condition in the American Saddlebred Horse can indeed be classified as JEB and corresponds to Herlitz JEB in humans. A diagnostic test was developed and nine of 175 randomly selected American Saddlebred foals from the 2007 foal crop were found to be carriers of the mutation (frequency of 0.026).
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