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Centronuclear Myopathy (Discovered in the Labrador Retriever)

Centronuclear Myopathy (CNM) is a type of muscle disease causing weakness and muscle wasting.

Found in

1 in 560 dogs

in our testing

Key Signs

Muscle weakness, Exercise intolerance, Ventroflexion, Skeletal muscle atrophy

Age of Onset

0 to 2 yrs

Juvenile onset

Inheritance

Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with CNM

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about CNM

In Labrador Retrievers, weakened or non-existent peripheral reflexes of the legs can occasionally be observed as early as 1 month of age, although more typically not until the puppies are 2 to 5 months old. At the age of 5 months, the affected puppies manifest decreased movement and exercise intolerance. The condition does not usually progress after the first year of life. In adult dogs, the most common signs are severe skeletal muscle atrophy especially in the areas of head, neck, and legs that limit the dog's ability to keep his head raised (ventroflexion) as well as abnormalities in posture and movements. Although the disorder limits the dog's athletic potential, it can still have a normal life span as a pet.

Treatment is supportive care and limiting exercise.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to develop. A carrier dog with one copy of the CNM mutation can be safely bred with a clear dog with no copies of the CNM mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the CNM mutation. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Please note: It is possible that disease signs similar to the ones caused by the CNM mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene PTPLA
Variant Insertion
Chromosome 2
Coordinate Start 19,371,988
Coordinate End 19,371,989

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Böhm, J., Vasli, N., Maurer, M., Cowling, B., Shelton, G. D., Kress, W., … Laporte, J. (2013). Altered Splicing of the BIN1 Muscle-Specific Exon in Humans and Dogs with Highly Progressive Centronuclear Myopathy. PLoS Genetics, 9(6). View the article

Gentilini, F., Zambon, E., Gandini, G., Rosati, M., Spadari, A., Romagnoli, N., … Gernone, F. (2011). Frequency of the allelic variant of the ptpla gene responsible for centronuclear myopathy in Labrador retriever dogs as assessed in Italy. Journal of Veterinary Diagnostic Investigation, 23(1), 124–126. View the article

Pelé, M., Tiret, L., Kessler, J. L., Blot, S., & Panthier, J. J. (2005). SINE exonic insertion in the PTPLA gene leads to multiple splicing defects and segregates with the autosomal recessive centronuclear myopathy in dogs. Human Molecular Genetics, 14(11), 1417–1427. View the article