X-Linked Myotubular Myopathy

What is XL-MTM?

This is a degenerative muscle disease first characterized in the Labrador Retriever. Affected dogs present as puppies with failure to thrive and weakness; this rapidly progresses to difficulty eating and breathing. XLMTM stems from a deficiency in the protein myotubularin, which is thought to be important for the development and maintenance of muscle cells. Loss of myotubularin causes muscle fiber damage and death, leading to replacement of the muscle mass with scar tissue. Unfortunately, there is currently no treatment for XLMTM.

What are the signs & symptoms that develop in affected dogs?

Affected puppies present with failure to thrive and weakness. This rapidly progresses to difficulty eating and breathing.

When do signs and symptoms develop?

Signs first appear in puppies.

How do vets diagnose this condition?

Genetic testing, clinical signs, and muscle biopsy can be used to diagnose this disorder.

How is this condition treated?

Unfortunately, there is currently no treatment for XLMTM and owners often choose euthanasia.

What actions should I take if my dog is affected?

Keeping your affected puppy comfortable and giving them the best quality of life you can are the only actions you can take at home.

More Information

This mutation was first characterized in the Labrador Retriever.

This mutation has a sex-linked recessive inheritance pattern, which means that the gene is on the X chromosome. Females have two X chromosomes and must inherit two abnormal copies to be affected with this disease. Males have only one X chromosome and either have a normal copy of the gene or the mutation.