DNA Test for PDP1 deficiency in Clumber and Sussex Spaniels
The Animal Health Trust announces the introduction of a DNA test for PDP1 deficiency in Clumber and Sussex Spaniels.
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 disease is characterised by exercise intolerance and post-exercise collapse. There may also be neurological symptoms. Treatment of affected dogs with a high-fat, ketogenic, diet has been suggested (see Abramson et al (2004)).
The mode of inheritance is autosomal recessive. A dog must therefore have two copies of the PDP1 deficiency form of the gene 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 can pass the PDP1 deficiency form of the gene onto their pups - such carrier dogs act as a reservoir of disease in the population and are only detectable by DNA testing. By having their dogs tested, breeders will be able to identify if and where the PDP1 deficiency form of the gene appears in their lines.
We do not recommend avoiding the use of carriers in breeding programmes entirely, this will needlessly restrict the size of the breeding population risking a detrimental effect on overall genetic variation within the breed. Rather, we 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 pups from carrier-clear matings will be clear and half carriers. No affected dogs will be produced from these matings. Any pups to be used for breeding should then also be DNA tested for PDP1 deficiency. 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. With breeders making good use of DNA testing, the PDP1 form of the gene can be effectively eradicated from the breeding population and no further testing will then be necessary for PDP1 deficiency.
Below is a summary of outcomes for possible matings for an autosomal recessive disease such as PDP1 deficiency. Please note that the percentages for each disease status, clear carrier or affected, are averages - many matings would need to be analysed to get exactly these figures. Nevertheless, they give a useful approximation for planning breeding programmes.
| sire | ||||
| clear | carrier | affected | ||
| clear | 100%clear | 50%clear+50%carrier | 100%carrier | |
| dam | carrier | 50%clear+50% carrier | 25%clear+50%carrier+ 25%affected |
50%carrier+ 50%affected |
| affected | 100%carrier | 50%carrier+ 50%affected |
100%affected |
The test is available now and information on submitting samples is given below. Breeders will be sent results identifying their dog as belonging to one of 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.
Samples submitted should be cheek swabs which are supplied free of charge from the address below. Samples should be sent together with a completed DNA Testing form and payment for each sample to Genetic Services, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU. DNA Testing forms can be downloaded from our web site (http://www.aht.org.uk). DNA Testing forms and kits for taking cheek swabs are available by phoning 08700 509144 or via e-mail to swab.request@aht.org.uk. The price of the PDP1 deficiency test is £65 inc VAT.
Enquiries should be made to Symone Ingram telephone +44 (0) 8700 509144 or fax +44 (0) 8700 502461 or via e-mail to dnatesting@aht.org.uk.
Cameron,J.M., Maj,M.C., Levandovskiy,V., MacKay,N., Shelton,G.D., Robinson,B.H. (2007) Identification of a canine model of pyruvate dehydrogenase phosphatase 1 deficiency. Molecular Genetics and Metabolism 90 15-23
Abramson,C.J., Platt,S.R. and Shelton,G.D. (2004) Pyruvate dehydrogenase deficiency in a Sussex spaniel. Journal of Small Animal Practice 45 162-165
