Pyruvate Dehdyrogenase Phosphate 1 (PDP1) Deficiency
Pyruvate Dehydrogenase Phosphate 1 (PDP1) is a genetic deficiency identified in Clumber and Sussex spaniels. The lack of the enzyme leads to a failure of the complex that is responsible for helping expel waste products from metabolism. When this complex does not function properly, the affected dog suffers from extreme exhaustion after very limited exercise.
The researchers who discovered the mutation reported that as many as 20% of all Clumber and Sussex Spaniels are carriers of the disease. A test is available for the disease so that breeders can make informed decisions to reduce the incidence of the disease.
The mode of inheritance for PDP1 is autosomal recessive. Therefore a dog must have two copies of the PDP1 deficiency form of the gene, one from each parent, to show symptoms. Dogs with one copy of the PDP1 deficiency form of the gene and one copy of the normal form do not show symptoms but they are carries and can pass the PDP1 deficiency form of the gene onto their puppies.
The Animal Health Trust in the United Kingdom does not recommend avoiding the use of carriers in breeding programs entirely. Doing so will restrict the size of the breeding population risking a detrimental effect on overall genetic variation within the breed. Rather, they suggest that once carriers have been identified they should be bred only to clear dogs, maintaining the good characteristics of those lines but avoiding the breeding of affected dogs. On average, half the puppies from carrier-clear matings will be clear and half carriers. No affected dogs will be produced from these matings. As testing proceeds an increasing number of dogs will be clear by heredity, that is they will come from stock known to be free of the PDP1 form of the gene.
When breeders submit a sample for testing, they will receive results indentifying their dog in one of these three categories:
CLEAR: the dog has 2 copies of the normal gene and will neither develop PDP1 deficiency, nor pass a copy of the PDP1 deficiency gene to any of its offspring.
CARRIER: the dog has one copy of the normal gene and one copy of the mutant gene that causes PDP1 deficiency. It will not develop PDP1 deficiency but will pass on the PDP1 deficiency gene to 50% (on average) of its offspring.
AFFECTED: the dog has two copies of the PDP1 deficiency mutation and is affected with PDP1 deficiency. It will develop PDP1 deficiency at some stage during its lifetime, assuming it lives to an appropriate age.
The research for this work was carried out at the University of Toronto (Cameron, J.M., et al 2007) where the mutation causing the disorder was identified in the gene pyruvate dehydrogenase phosphatase 1.
The test for PDP1 is available from the Animal Health Trust in the United Kingdom, the University of Missouri - Animal Molecular Genetics Laboratory, and VetGen, LLC.
For more information on the test visit the laboratory website:
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