Results
Pet health test
Muscular Dystrophy (DMD gene, Cavalier King Charles Spaniel)

Muscular Dystrophy (DMD gene, Cavalier King Charles Spaniel)

Muscular dystrophy is an X-linked inherited disease characterized by progressive muscle degeneration and muscle weakness. This disorder mainly affects males and results from mutations in the dystrophin gene.

Symptoms

The initial clinical signs of muscular dystrophy usually manifest at around 8 weeks of age. At this stage, dogs show muscle weakness, difficulty tolerating exercise and a stiff gait. As the weeks go by, the muscle atrophy worsens and symptoms such as generalized weakness, enlargement of the tongue and difficulties in swallowing and eating are added. In addition, affected dogs suffer from respiratory problems, brief episodes of neck muscle spasms and are at risk of developing muscular heart disease, which can trigger a fatal outcome.

Disease Management

Unfortunately, there is currently no specific therapy that cures muscular dystrophy. However, approaches such as anabolic supplements, growth factors and stem cell therapy have been investigated and may provide benefits by delaying or ameliorating the clinical signs of the disease. It is important to note that the efficacy of these approaches is not guaranteed and they still require further research to understand their true potential.

Genetic basis

This disease follows an X-linked recessive mode of inheritance. Recessive X-linked inheritance means that female dogs must receive two copies of the mutation or pathogenic variant (one from each parent) to develop the disease, whereas males need only one copy of the mutated gene or variant from the dam to develop the disease. Male dogs usually show symptoms of the disease. Each male puppy born to a mother carrying the mutation has a 50% chance of inheriting the mutation and thus the risk of developing the disease. Bitches that do not carry the mutation are not at increased risk of having affected puppies. Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.

Technical report

Muscular dystrophy is a disorder characterized by progressive degeneration of muscle fibers, caused by mutations in the DMD gene, responsible for the production of dystrophin. Dystrophin is an essential protein that has a dual function: it acts as a structural component of muscles and also connects the contractile apparatus to the sarcolemma. Thus, dystrophin is considered to provide mechanical stability during muscle contraction. The mutations causing muscular dystrophy occur in the dystrophin gene, although there may be molecular differences depending on the affected breed. In the case of the Cavalier King Charles Spaniel, a nonsense mutation (c.7294+5G>T) has been identified in exon 50, which results in the deletion of this exon and produces a truncated protein. This disease is also known as Golden Retriever muscular dystrophy, as it was in this breed that the condition was first discovered in 1992. Over the years, different variants have been described in different breeds, although not all mutations identified to date are analyzed in our test.

Most affected breeds

Cavalier King Charles Spaniel

Bibliography

Walmsley GL, Arechavala-Gomeza V, Fernandez-Fuente M,et al. A duchenne muscular dystrophy gene hot spot mutation in dystrophin-deficient cavalier king charles spaniels is amenable to exon 51 skipping. PLoS One. 2010 Jan 13;5(1):e8647.