Test Detail

Severe X-linked congenital myopathy caused by variants in the MTM1 gene (myotubularin 1). It is characterized by generalized muscle weakness and gait abnormalities due to defective muscle fibre development (fibres with central nuclei). The first and only case described in the cat corresponds to a male Maine Coon; the disease is known mainly in dogs and humans.

A single published case (male Maine Coon). The variant was not identified in 339 cats from the 99 Lives project, nor in 11 unrelated Maine Coons, nor in 2 additional cats (Kopke et al., 2022). Limited data.

- In a male kitten with progressive weakness, consider congenital myopathy and confirm with genetics and biopsy.\n- Do not breed with known carriers of the variant.\n- Carrier females can transmit the variant to offspring; genetic counselling must be individualized due to the limited evidence.

First report in the cat; the evidence is limited to one case and must be interpreted with caution. Rule out other causes of weakness (e.g. spinal muscular atrophy due to LIX1, which was negative in the case). Do not confuse with other congenital myopathies. Confirmation requires clinical correlation, histopathology and genetics.

1. Kopke MA, Shelton GD, Lyons LA, et al. X-linked myotubular myopathy associated with an MTM1 variant in a Maine coon cat. J Vet Intern Med. 2022;36(5):1898-1903. PMID: 35962713.
2. OMIA:001508-9685. Myotubular myopathy 1 in Felis catus. https://omia.org/OMIA001508/9685/