Ceroid Lipofuscinosis in Border Collies
Ceroid lipofuscinosis is an inherited neurodegenerative disease found in a number of breeds of dog. The mutation causing the form of the disease found in Border Collies has recently been identified in the laboratory of Dr Alan Wilton, University of New South Wales, Sydney, Australia.
The mutation, or change to the structure of the gene, probably occurred spontaneously in a single dog but once in the population has been inherited from generation to generation like any other gene. The disorder shows an autosomal recessive mode of inheritance: two copies of the defective gene (one inherited from each parent) have to be present for a dog to be affected by the disease. Individuals with one copy of the defective gene and one copy of the normal gene - called carriers - show no symptoms but can pass the defective gene onto their offspring. When two apparently healthy carriers are crossed, 25% (on average) of the offspring will be affected by the disease, 25% will be clear and the remaining 50% will themselves be carriers
The DNA test not only diagnoses dogs affected with this disease but can also detect those dogs which are carriers, displaying no symptoms of the disease but able to produce affected pups. Under most circumstances, there will be a much greater number of carriers than affected animals in a population. It is important to eliminate such carriers from a breeding population since they represent a hidden reservoir of the disease that can produce affected dogs at any time.
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 ceroid lipofuscinosis, nor pass a copy of the ceroid lipofuscinosis 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 ceroid lipofuscinosis. It will not develop ceroid lipofuscinosis, but will pass on the ceroid lipofuscinosis gene to 50% (on average) of its offspring.
AFFECTED: the dog has two copies of the ceroid lipofuscinosis mutation and will be affected with ceroid lipofuscinosis.
Carriers can still be bred to clear dogs. On average, 50% of such a litter will be clear and 50% carriers; there can be no affecteds produced from such a mating. Pups which will be used for breeding can themselves be DNA tested to determine whether they are clear or carrier.
Samples for testing (2mls EDTA blood), should be sent together with a completed DNA Testing form and payment of £65 inc VAT (cheque or credit card) for each sample to Genetic Services, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU.
DNA testing forms can be downloaded by clicking here.
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.
