Cardiac Laminopathy (CLAM) in the Nova Scotia Duck Tolling RetrieverQuick Summary
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Phenotype: Affected dogs present with dilated cardiomyopathy at a young age and typically experience sudden death within the first year of age.
Mode of Inheritance: Autosomal recessive
Alleles: N = Normal, CLAM = Cardiac Laminopathy
Breeds appropriate for testing: Nova Scotia Duck Tolling Retriever
Explanation of results:
• Dogs with N/N genotype are expected to not have cardiac laminopathy. They cannot transmit this CLAM variant to any of their offspring.
• Dogs with N/CLAM genotype are carriers of cardiac laminopathy. They will transmit this CLAM variant to 50% of their offspring. Matings between two carriers of CLAM may, on average, produce 25% of puppies with cardiac laminopathy.
• Dogs with CLAM/CLAM genotypes are homozygous for the CLAM variant and will have cardiac laminopathy which is ultimately a fatal condition.
Sample Collection
Dog DNA tests are carried out using cells brushed from your dog's cheeks and gums. The preferred cytology brushes are sent to you by mail, or you may provide your own brushes. For accepted alternative brushes, click here
We recommend waiting until puppies are at least three weeks old before testing.
Step-By-Step:
- Make sure the dog has not had anything to eat or drink for at least 1 hour prior to collecting sample.
- When swabbing puppies, isolate each puppy from the mother, littermates and any shared toys for 1 hour prior to swabbing. Puppies should not have nursed or eaten for 1 hour prior to collecting sample.
- If collecting samples from more than one dog, make sure to sample one dog at a time and wash your hands before swabbing another dog.
- Label brush sleeve with name or ID of dog to be sampled.
- Open brush sleeve by arrow and remove one brush by its handle.
- Place bristle head between the dog’s gums and cheek and press lightly on the outside of the cheek while rubbing or rotating the brush back and forth for 15 seconds.
- Wave the brush in the air for 20 seconds to air dry.
- Insert brush back into sleeve.
- Repeat steps 5 - 8 for each unused brush in sleeve on a fresh area of cheek and gums. Make sure to use and return all brushes sent by the VGL. In most cases, it will be 3 brushes per dog. If using interdental gum brushes, please note that the VGL requires 4 brushes per dog and only moderate or wide interdental gum brushes are accepted.
- Do not seal brushes in sleeve.
- Place all samples in an envelope and return to the address provided.
ATTENTION:
- Do not collect saliva/drool – the key to obtaining a good sample is getting cheek cells on the swab
- Do not rub swab on the dog’s tongue or teeth – this will result in poor quality sample
- Do not collect a sample from a puppy that has recently nursed – the mother’s genetic material can rub off on the puppy’s mouth and contaminate the sample
Cardiac Laminopathy (CLAM) is caused by a deletion in the LMNA gene (p.Asp576ThrfsTer124). The condition appears to be inherited in an autosomal recessive manner, meaning that two copies of the CLAM variant are needed for the disease to be expressed. Affected dogs are homozygous for the variant and present with sudden death associated with dilated cardiomyopathy. No treatment is available at this time and the condition is typically lethal in young adult dogs. Affected homozygous dogs studied to date experienced sudden death before 2 years of age.
The genetic variant causing this disease was discovered by Dr. Danika Bannasch here at UC Davis, in the School of Veterinary Medicine. Dr. Bannasch shared her findings with the VGL pre-publication so that we could more rapidly offer genetic testing to toller breeders. The recently published study also described a single heterozygous dog that experienced sudden death at 5 years of age. The dog presented with myocardial fibrosis (scarring of the heart muscle) suggesting that the presence of one copy of this LMNA deletion may also lead to cardiac abnormalities, although no other affected heterozygous dog has been identified to date.
Testing recommendations: DNA testing for cardiac laminopathy can determine the genetic status of dogs. Dogs with one copy of the CLAM variant are normal but are carriers. Matings between two carrier dogs may, on average, produce 25% of puppies with cardiac laminopathy, which is a lethal condition in young adult dogs.
