X-linked Myotubular Myopathy (XLMTM) in Rottweilers

Quick Summary

X-linked myotubular myopathy in Rottweilers is an inherited muscle disease that manifests with severe, progressive muscle atrophy in puppies.

Phenotype: Puppies appear clinically normal at birth but muscle atrophy is often apparent by 7 weeks of age. Affected puppies often appear noticeably smaller than littermates and may have problems with coordination and mobility. Within weeks, the puppies may have difficulty in holding their head up and may an exhibit an inability to stand or may collapse after exertion. The disease is severe and progressive with most affected dogs being euthanized before 6 months of age.

Mode of Inheritance: X-linked recessive

Alleles: N = Normal, MTMR = X-linked myotubular myopathy

Breeds appropriate for testing: Rottweiler

Explanation of Results:

Males only have one X chromosome whereas females have two, therefore possible genotypes will differ by sex.

  • Female dogs with N/N genoytpe and male dogs with N genotype will not have X-linked myotubular myopathy, and cannot transmit this variant to their offspring.
  • Female dogs with MTMR/N genotype will not have X-linked myotubular myopathy, but are carriers. If a carrier female is bred to a normal (N) male, all female puppies will be normal but 50% of them will be carriers. Among male puppies from this type of cross, 50% will be normal and 50% will be affected by X-linked myotubular myopathy.
  • Female dogs with MTMR/MTMR genotype and male dogs with MTMR genotype will have X-linked myotubular myopathy, a severe, progressive muscle disease.

Results of this test can be submitted to the OFA (Orthopedic Foundation for Animals)

Price

$50 one test per animal
$30 as additional test (same animal)

Panels Available
Additional Details

X-linked myotubular myopathy (XLMTM) is an inherited muscle disease that affects Rottweilers. The disease is caused by a defect in the myotubularin protein, a component of muscle cell membranes, which ultimately inhibits their ability to contract. Puppies appear clinically normal at birth but muscle atrophy is often apparent by 7 weeks of age. Affected puppies often appear noticeably smaller than littermates and may have problems with coordination and mobility. Within weeks, affected puppies may have difficulty in holding their head up and may an exhibit an inability to stand or may collapse after exertion. The disease is severe and progressive with most affected dogs being euthanized before 6 months of age.

The Rottweiler XLMTM causal missense mutation (c.1151A>C), reported here as MTMR, occurs in exon 11 of the myotubular myopathy 1 (MTM1) gene. The disease is inherited in an X-linked recessive fashion. Females with two defective copies will show disease. Clinical signs are absent in females with one normal and one affected gene (carriers). Males have only one X chromosome, and therefore males that inherit the affected allele will show disease. If the inherited allele is normal, males do not have the disease.

Testing for for XLMTM in Rottweilers assists clinicians with diagnosis of myotubular myopathy and helps breeders identify carrier females to avoid mating pairs that can produce affected dogs. When a carrier female is bred to a normal male, all female puppies will be normal but 50% of them will be carriers. Among male puppies from this type of cross, 50% will be normal and 50% will be affected.

 

Note: This test does not detect the MTM1 mutation that causes a similar disease in Labrador Retrievers. A separate test for Labrador Retrievers is available through the VGL.
Turnaround Time
5-10 business days

Species

Dog

Breed

Type of Test

Results Reported As
Test Result X-linked Myotubular Myopathy

N/N

Normal female. No copies of the Rottweiler MTM1 mutation.

MTMR/N

Carrier female. 1 copy of the Rottweiler MTM1 mutation.

MTMR/MTMR

Affected female. 2 copies of the Rottweiler MTM1 mutation.

N

Normal male. No copy of the Rottweiler MTM1 mutation.

MTMR

Affected male. 1 copy of the Rottweiler MTM1 mutation.

References

Shelton, G.D., Rider, B.E., Child, G., Tzannes, S., Guo, L.T., Moghadaszadeh, B., Troiano, E.C., Haase, B., Wade, C.M., & Beggs, A.H. (2015). X-linked myotubular myopathy in Rottweiler dogs is caused by a missense mutation in Exon 11 of the MTM1 gene. Skeletal Muscle 5:1. doi: 10.1186/s13395-014-0025-3