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Hypomyelination is a neurological disorder causing muscle tremors and movement difficulties.

Key Signs

Action tremors, Locomotory difficulties

Age of Onset

At birth

Present at birth


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

Moderate-high likelihood

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

What to Do

Here’s how to care for a dog with Hypomyelination

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 Hypomyelination

The onset of signs typically occurs at 1-2 weeks of age. A characteristic sign of hypomyelination is muscle tremor. The severity of the tremor can vary between individuals, however body tremors tend to worsen with activity (action tremor) and decline during rest. Affected dogs are able to walk, but they may have a "hopping-like movement of the hind legs. Affected puppies usually improve by 3-4 months of age, although some dogs may continue to exhibit a mild persistent tremor of the hind legs.

Treatment is supportive care and assistance with daily activities as needed depending on the severity of the dog's clinical signs.

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 occur. A carrier dog with one copy of the Hypomyelination mutation can be safely bred with a clear dog with no copies of the Hypomyelination mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the Hypomyelination mutation. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the Hypomyelination mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene FNIP2
Variant Deletion
Chromosome 15
Coordinate 55,928,287

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Pemberton, T. J., Choi, S., Mayer, J. A., Li, F. Y., Gokey, N., Svaren, J., … Duncan, I. D. (2014). A mutation in the canine gene encoding folliculin-interacting protein 2 (FNIP2) associated with a unique disruption in spinal cord myelination. Glia, 62(1), 39–51. View the article