The clinical signs of X-linked myotubular myopathy can be seen in puppies as young as 10-19 weeks of age. Pelvic limb weakness is typically observed as one of the first signs. Affected dogs also lack patellar reflexes. XLMTM is characterized by rapidly progressing muscle weakness and muscle atrophy. Affected dog won't be able to rise and move unassisted within a few weeks of the onset of clinical signs and may also have difficulties chewing and swallowing. Excessive autophagy and prominent autophagic vacuoles are seen upon histopathology.

As the disorder is progressive, the welfare of affected dogs should be monitored closely. Owners of affected dogs should be advised that their dog will require assistance with movement and that clinical signs are likely to progress rapidly.

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 disorder is X-linked recessive, meaning the genetic variant is found on the X chromosome. Given males only have one X chromosome, a single affected copy will increase the risk of being diagnosed with the disorder. Females typically require two copies to be at an elevated risk. Use of dogs with one or two copies of the variant is not recommended for breeding as there is a risk that the resulting litter will contain affected puppies. Please note: It is possible that clinical signs similar to the ones caused by this variant could develop due to a different genetic or clinical cause.