Centronuclear Myopathy (CNM) in Labrador Retrievers

Quick Summary

Centronuclear myopathy is a hereditary myopathy of Labrador Retrievers characterized by generalized loss of muscle tone and control.

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Phenotype: Signs of centronuclear myopathy include generalized loss of muscle tone and control, exercise intolerance, and an awkward gait. CNM typically manifests in puppies at 2-5 months of age.

Mode of Inheritance: Autosomal recessive

Alleles: N = Normal, CNM = Centronuclear myopathy

Breeds appropriate for testing: Labrador Retriever

Explanation of Results:

  • Dogs with N/N genotype will not have centronuclear myopathy and cannot transmit this CNM variant to their offspring.
  • Dogs with N/CNM genotype will not be affected by centronuclear myopathy, but are carriers. They will transmit this CNM variant to 50% of their offspring. Matings between two carriers are predicted to produce 25% centronuclear myopathy-affected puppies.
  • Dogs with CNM/CNM genotype will have centronuclear myopathy.

Results of this test can be submitted to the OFA (Orthopedic Foundation for Animals)

Turnaround Time
At least 15 business days; may be delayed beyond 15 business days if sample requires additional testing, or a new sample is requested.
Price

$55 single test per animal ($5 discount on 3 or more dogs)
$25 as additional health test on same animal

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.

 

Dog having its cheeks and gums brushed for DNA samples
Cheek and gum brushing technique for canine DNA sample collection

Step-By-Step:

  1. Make sure the dog has not had anything to eat or drink for at least 1 hour prior to collecting sample.
  2. 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.
  3. 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.
  4. Label brush sleeve with name or ID of dog to be sampled.
  5. Open brush sleeve by arrow and remove one brush by its handle.
  6. 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.
  7. Wave the brush in the air for 20 seconds to air dry.
  8. Insert brush back into sleeve.
  9. 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.
  10. Do not seal brushes in sleeve.
  11. 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
Additional Details

Centronuclear myopathy (CNM) is a hereditary myopathy of Labrador Retrievers resulting from a mutation in the protein tyrosine phosphatase-like member A gene (PTPLA). PTPLA codes for a dehydratase enzyme that functions in the production of long chain fatty acids, these molecules are thought to be involved in muscle homeostasis. While the precise role of PTPLA in this disease is unknown, the CNM mutation has been shown to lead to a reduction in normal gene product.

The disease is inherited in an autosomal recessive fashion with both sexes equally affected.

This condition has also been called type II muscle fiber deficiency, autosomal recessive muscular dystrophy, and hereditary myopathy.

CNM typically manifests in puppies at age 2-5 months. Signs of CNM include generalized loss of muscle tone and control, exercise intolerance, and an awkward gait. Dogs with one normal copy and one mutant copy of the gene (heterozygous) do not display signs. Breeding two carriers is predicted to produce 25% affected offspring and 50% carriers of the disease.

Testing for CNM can assist clinicians, owners, and breeders in identifying affected and carrier dogs. Breeders can use results from the test as a tool for selection of mating pairs to avoid producing affected dogs.

 

Note: This test is specific for the CNM mutation described in Labrador Retrievers.